ALBERT

Notes: Abstract The previously reported IR study on 21 different 1-substituted 3-acylamino-2-pyrazolines assumed thecis configuration for the amide groups. In order to establish the configuration, X-ray structure determinations of two model compounds (1-phenyl-3-benzoylaminopyrazoline, monoclinic,a = 5.218,b = 8.830,c = 14.372 Å, β = 90.7 °,Z = 2, P2 1; 1-benzyl-3-acetaminopyrazoline, monoclinic,a = 9.529,b = 13.679,c = 18.112 Å, β = 96.7 °,Z = 8,P21/n) were performed. Both structures were solved by direct methods, and refined to a finalR = 0.075 for 710 andR = 0.122 for 2140 observed reflections. The configurations of the amide groups were found to betrans.

Notes: Abstract The crystal structure of 2,4-dinitrophenyl phenylsulfide, C12H8N2O4S, has been determined by single crystal X-ray diffraction. The crystals are monoclinic, space groupP2 1/n, Z = 8, witha = 10.670(2),b = 8.381(4),c = 27.998(18) Å, and β = 100.44(4) °. There are two crystallographically independent molecules per asymmetric unit. All intensity measurements were made at room temperature on an Enraf-Nonius CAD-4 automatic diffractometer using monochromatized MoKα radiation. The structure was solved by direct methods and refined to a finalR value of 0.032. The two independent molecules have nearly identical geometries, with the most notable difference being the torsion angles involving the sulfur atoms. Thepara-nitro groups are more nearly in the planes of the central phenyl rings than are theortho-nitro groups although there may be nonbonded attractions between the latter. The two phenyls of each molecule are nearly at right angles to each other, as necessitated by steric forces involvingortho hydrogens. The characteristic distortions of the central phenyl rings caused by differing substituent electronegativities and degrees of conjugation are noted. The13C-NMR spectrum of the compound was assigned by comparison of calculated with observed chemical shift data. Calculated chemical shifts were obtained by incrementation of the chemical shifts of diphenylsulfide with standard nitro group additivities which were adjusted for the sulfur-nitro group interaction. Where necessary, assignments were confirmed with selective excitation spin-coupled subspectra. Solution behavior of the molecule was determined from spin-lattice (T 1) relaxation measurements which showed the unsubstituted ring to reorient anisotropically about the C(21)-C(24) bond axis while the substituted ring appears to be governed by the overall isotropic reorientation of the molecular framework, indicating that the sulfur-nitro group interaction restricts anisotropic reorientation about the C(11)-C(14) bond axis.

Notes: Abstract The reactions in THF or benzene between Cp2 M (HgX)2 ·x HgX 2 (M = Mo or W; O ⩽x ⩽ 1;X − = Cl−, Br−, I−, SCN−, OAc−) and sodium diethyl-dithiocarbamate $$\begin{gathered} Cp_2 M\left( {HgX} \right)_2 .xHgX_2 + \left( {2 + x} \right)Nadtc \rightleftharpoons Cp_2 M\left( {Hgdtc} \right)_2 \hfill \\ + xHg\left( {dtc} \right)_2 + \left( {2 + x} \right)NaX \hfill \\ \end{gathered} $$ as well as between Cp2 MH2 and mercury diethyldithiocarbamate $$x2Cp_2 MH_2 + 2Hg\left( {dtc} \right)_{2 - } Cp_2 M\left( {Hgdtc} \right)_2 + \left\{ {Cp_2 Mdtc} \right\}dtc + 2H_2 $$ give the compound Cp2 M(Hgdtc)2 (dtc is diethyldithiocarbamate anion). The structure of the molybdenum complex determined by the X-ray method (a = 12.776(4),b = 7.835(4),c = 27.397(7) Å β = 111.18(2) °; space groupC2/c (No. 15);Z = 4) consists of discrete molecules occupying special positions on two-fold axes. A short Mo-Hg distance of 2.643(8) Å and a rather long Hg-S one of 2.50(2) Å were found. The diethyldithiocarbamate anion behaves like a monodentate ligand. IR and1H,13C NMR results agree with the molecular structure determination and confirm a weak bond between mercury and dithiocarbamate and strong molybdenum-mercury bond. A considerable solvent effect (C6D6 vs. CDCl3 solutions) has been observed on the1H chemical shifts of both dtc and Cp ligands. The {Cp2Modtc}+ X − (X = dtc and PF6) complexes, although not obtained in a pure form, were included in the discussion of the spectroscopic features of those with theM-Hg bonds.

Notes: Abstract The crystal and molecular structure ofH 4a ,H 9a -cis-H 9,H 9a -trans-2-methyl-9-phenyl-2, 3,4,4 a ,9,9 a -hexahydro-1H-indeno[2,1-c]pyridine hydrochloride was determined. The compound crystallizes in the orthorhombic space groupPbca, with eight molecules in the unit cell of dimensionsa = 10.461(2),b = 20.141(10), andc = 15.469(3) Å. Intensity data were measured using Mo radiation and a θ−θ scan method. The structure was solved by direct methods and refined by least-squares techniques to a finalR of 4.6%. Thecis-trans isomer has higher antihistamine activity compared to thecis-cis isomer but is less active than phenindamine, the 2,3,4,9-tetrahydro derivative. The bond distances in thecis-trans andcis-cis derivatives are identical so that the differences in activity must be related to differences in conformation. The difference in the conformation is discussed from a receptor-site view of the two molecules.

Notes: Abstract The crystal structure of the muscle relaxant stercuronium iodide in the form of its ethanol solvate C26H43N2 +I− · C2H5OH, has been determined by the heavy-atom method and refined by block-diagonal least-squares toR o = 0.062 for 1941 observed reflections andR = 0.079 for a total of 2420 reflections measured on a four-circle diffractometer in the ω/2θ scanning mode. The crystals are monoclinic,P21,a = 15.386(5),b = 11.377(4),c = 8.307(3) Å, β = 98.22(2) °,Z = 2. RingsA andB in the modified conessine skeleton are both highly symmetrical half-chairs, ringC is in the chair conformation, and ringsD andE are highly symmetrical envelopes. The pyrrolidine ringE fused to ringD is roughly perpendicular to the steroid skeleton formed by ringsA toD. The N+---N distance of 10.76 Å is within the usual range required for potent neuromuscular blocking. Semiquantitative results are presented which suggest that the site of the tertiary N atom in ringE is not heavily congested by neighboring atoms in the molecule and may therefore be susceptible to protonation under physiological conditions. This could account for the relatively high drug potency of stercuronium.

Notes: Abstract The crystal structure of 2-aminophenol has been redetermined from automatic diffractometer data in order to locate the hydroxyl and amino hydrogens and confirm the nature of the intermolecular hydrogen bonding. Crystals are orthorhombic, space groupPbca, witha =19.751(6),b = 7.250(3), andc = 7.852(5) Å, and eight molecules per cell. The structure was solved by Multan and refined to a conventionalR value of 0.030. The molecular geometry compares well with previously reported structures of related species. The molecules are hydrogen bonded from OH to N to form chains parallel to theb axis, with these chains linked together to form sheets by NH to O hydrogen bonds essentially parallel toc. The NH - O hydrogen bonds are 0.33 Å longer than the OH - N ones, and an explanation for this is provided which incorporates newly computed values for atomic electronegativities. Pairs of molecules are mutually hydrogen bonded across inversion centers. There are large cavities between the sheets which could conceivably result in easy intercalation of small foreign molecules, much as in the clathrates formed by urea and β-quinol.

Notes: Abstract Crystals of 5-ethyl-5-(3′-methylbut-2′-enyi) barbituric acid, mp 154° C, are monoclinic, space groupP21/c witha = 11.590(3) Å,b = 22.188(10),c = 10.195(4), β = 108.949(1)°, and Z = 8. The crystal structure was solved by direct methods and Fourier and difference-Fourier techniques, and refined by block least-squares procedure toR = 0.071 for 2983 observed data. Of the two molecules in the asymmetric unit, one is disordered and has been explained in terms of three different conformations of the 3′-methylbut-2′-enyl group. The molecules form ribbonlike structures, held together by N-H ... O=C hydrogen bonds. These ribbons are held together to form bilayers of barbiturate rings by van der Waals interactions between the 5-ethyl groups, with the bilayers held together by van der Waals interactions between the 5-(3′-methylbut-2′-enyl) groups.

Notes: Abstract The crystal structure of bromofluoroacetic acid has been determined from three-dimensional counter data, and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupP21/c, witha = 8.529(4),b = 5.632(3),c = 9.500(4) Å,β = 105.52(4) °, andD x = 2.37 g cm−3 forZ = 4. The finalR factor for 654 independent observed reflections is 0.081. The compound exists as hydrogen-bonded dimers in the solid state.

Notes: Abstract trans-5-Ethyl-5-but-1′-enyl barbituric acid, mp 112° C, is triclinic, space groupP¯1 witha = 8.228(1),b = 10.445 (2),c = 7.265(1) Å, α = 111.165(1), β = 105.512(1), γ = 95.079(1)°, and Z = 2. The crystal structure was determined by direct methods and refined to R = 0.047 by full-matrix least-squares procedures for 2308 observed diffraction maxima. The molecules form ribbonlike structures alongb, held together by N-H ... O=C hydrogen bonds and van der Waals forces between an alternating sequence of ethyl and but-1-enyl groups.

Notes: Abstract Crystals oftrans-5-ethyl-5-(1′,3′-dimethylbut-1′-enyl) barbituric acid (13M1TB), mp 183° C, are triclinic witha = 7.677(2),b = 10.393(3),c = 9.176(3) Å, α = 104.331(1), β = 106.919(1), γ = 96.494(1)°, space group P, with two molecules in the unit cell. The structure was solved by direct methods and refined by least-squares procedures toR = 0.050 for 2809 observed diffraction maxima. The 5-ethyl group is oriented under the barbiturate ring with the orientation of the but-1-enyl group directed away from the ring. This orientation is determined by the 1′-methyl substituent. The molecules are linked together by N-H ... O=C hydrogen bonds across inversion centers, thus forming single ribbons alongb. Adjacent ribbons are held together in theac plane by van der Waals interactions between alternating ethyl and l′,3′-dimethylbut-l′-enyl groups.

Notes: Abstract The distance between two equilibrium proton sites in symmetric OHO bonds and its isotopic variation, determined from precise neutron-diffraction data, has been compared with the predicted values which were derived previously by the author using correlation curves in hydrogen-bond parameters. It is shown that a fairly good agreement was obtained between the observed and the predicted values, indicating the validity of the empirical relations.

Notes: Abstract The crystal structure of vanadocene has been determined from counter data, and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupP21/n witha = 9.269(3),b = 8.020(3),c = 5.892(2) Å, β = 91.21(3)°, andD x = 1.37 gcm-3 for Z = 2. The finalR value for 583 observed reflections is 0.031. The vanadium atom resides on a crystallographic center of inversion. The cyclopentadienyl groups are statistically disordered 70–30%. The average vanadium-carbon (η5) bond distance is 2.26(2) Å.

Notes: Abstract Crystals of C20H16N2O2 are orthorombic:P212121,a = 28.1364(21),b = 7.6474(2),c = 7.5376(2) Å,Z = 4, μ = 6.4 cm−1 (CuKα radiation), andM = 316.36. The structure has been solved by direct methods and refined by two-block least-squares toR = R w = 0.042. The conformation of ringB is a distorted envelope at N(10), and the phenyl rings have acis configuration with respect to the pyridazine ring. Thermal motion of the molecule has been analyzed in terms of the rigid-body TLS model.

Notes: Abstract Crystals of the title compound, C17H14BrNO, are monoclinic, with space groupP21/a,a = 14.314(5),b = 15.009(11),c = 6.596(3) Å, and β = 102.39(3) °. Diffraction data were collected with CuKα radiation to a Bragg angle of 77 °. The structure was solved by the heavy-atom method and refined to anR index of 0.059 for 2129 reflections. In agreement with NMR results, the C=O group is orientedanti to the benzene ring, and the methyl group at C(6) is axial. Unlike 1-(p-bromobenzoyl)-2-methyl-1,2,3,4-tetrahydroquinoline, the heterocyclic ring assumes a well defined half-chair conformation. Except for C(5) and the methyl group at C(6), the whole molecule is very nearly planar.

Notes: Abstract The X-ray crystal structure of the title compound, C10H14S1, is reported. Crystals are monoclinic, space groupP21/c with Z = 2 in a unit cell of dimensionsa = 8.517(2),b = 6.109(1),c = 10.730(1) Å, and β = 107.01(2)°. The structure was solved by direct methods and refined by full-matrix least squares toR = 0.032 for 1059 diffractometer data. The bicyclic molecular framework contains eight π-electrons and is planar and rigid, all relevant interatomic distances corresponding to either ideally single or ideally double bonds. The first UV absorption observed at 3.61 eV, and tentatively described as due to a π(bg) → π*(a u*) electron transition, is significantly higher than that found in a related aromatic tetraphenylthienothiophene system.

Notes: Abstract Crystals of the phenylurethane derivative of a novel bicyclic lactone, C18H21NO8, have an orthorhombic unit cell of dimensionsa = 8.648(2),b = 11.041(7),c = 19.589(4) Å, and belong to space groupP212121. The structure was solved by direct methods and was refined by the block diagonal approximation to a finalR value of 0.034 using 1035 reflections. The structure is made up of a six-membered lactone ring, in the boat conformation,cis-fused to a five-membered oxolane ring. The phenylurethane and the methoxy groups aretrans to each other, while the ethyl carboxylate group is attached in equatorial position.

Notes: Summary Floor Loading and Movement Along the Coalface Total roof to floor convergence, floor loading, horizontal and vertical movements of floor along three selected longwall faces were investigated. Empirical equations expressing the above noted linearly time-dependent factors in strata mechanics are developed. It was observed that the contribution of floor to the total roof to floor closure is between 31 to 63%, dependent upon the strength of roof and floor layers encountered.

Notes: Résumé Anisotropie de la dilatance des roches schisteuses Les petites déformations de schistes ardoisiers, mesurées au cours d'essais de compressions triaxiales, montrent une orthotropie de révolution élastique initiale dont les coefficients varient avec la pression de confinement. Lorsque la déformation croît, comme pour les roches pseudo-isotropes, mais seulement pour certaines plages d'orientation de la structure par rapport au tenseur contrainte, prend naissance le mécanisme de dilatance. Le seuil de dilatance dépend de cette orientation et de la pression de confinement. La dilatance croît avec la contrainte suivant une loi proche du second degré.

Notes: Summary On the Determination of Some Important Geotechnical Joint Properties by Means of Integral Geometry Simple equations are presented which are useful to evaluate properties of joints important in rock mechanics, e. g. the length of linear of intersected joints, the joint area, the joint opening, the joint volume, and the edge length of rock blocks defined by joints. Also, the integral-geometrical derivation of the equations is presented to compare these with previously published expressions for such joint properties. Methods of measurement are illustrated to record the features from which the joint properties are evaluated: simply determinable numbers of points and lengths along measuring lines and numbers of points on measuring areas. The potential usefulness of the integral-geometrically derived equations is tested on a weathering profile of a Upper Devonian siltstone.

Notes: Summary Approach to Complete Limit Equilibrium Analysis for Rock Wedges — The Method of “Artificial Supports” Since the movement of rock wedges or blocks is the primary phenomenon in rock mass failure, it is convenient to use limit equilibrium approaches for stability analysis. In spite of their wide use, limit equilibrium analysis is often restricted due to: 1) the usual procedural simplifications (regarding geometry, force application, failure modes), and 2) basic deficiencies of the limit equilibrium approach (the fundamentally indeterminate rigid body problem requires assumptions regarding the force reactions). The method of artificial supports intends to circumvent or reduce many of these restrictions. In particular, the problem of unknown force distribution on the supporting plane is reduced by specifically considering and optimizing a variety of reactions on these planes. All sliding modes of failure — i. e., translational, free and restrained rotational sliding — can be correctly modelled. Particularly significant is the result that the usual assumption oftranslational sliding can be incorrect andunsafe, if forces other than the weight are significant. The methodologies employed in the artificial support model can be extended to all modes of failure, i. e., lifting off and toppling in addition to the previously mentioned sliding modes; this is demonstrated with a procedure for a “complete” stability analysis for a 2-joint wedge.

Notes: Zusammenfassung Das neotektonische Spannungsfeld in den Regionen von Shaanxi, Gansu, Ningxia und Qinghai (China) Geologische, seismologische, geodätische und geomorphologische Daten wurden verwendet, um die Richtung der überregionalen, neotektonischen Hauptnormalspannungen im nördlichen Zentralchina zu bestimmen. Es wird gezeigt, daß die maximale Druckspannung eine NE-SW-Richtung hat (N 40° E). Im Detail scheint es eine Rotation der maximalen Druckspannungsrichtung von N 7° E im Ladakh bis N 33° E im chinesischen Westxizang und bis ca. N 70° E im Südwesten der hier untersuchten Region zu geben. Dies kann ein Hinweis dafür sein, daß, abgesehen vom Effekt einer Kollision zwischen der eurasischen und indischen tektonischen Platte, sich auch der Effekt der Kollision zwischen der eurasischen und pazifischen Platte bemerkbar macht.

Notes: Summary Size Distributions of Rock Blocks from Measurements on Rock Faces In this model rock blocks are regarded to have spherical shape and they are described by a distribution of diameters of spheres. The measured quantities are the lengths of chords which are recorded along measuring lines across rock faces. The volume fractions of the size classes of rock blocks are derived from the distribution of chord lengths. Three methods are discussed for obtaining the sphere diameter distribution from counts of chord numbers on sections. An example is given for the size distribution of rock blocks in a weathering profile of an Upper Devonian siltstone.

Notes: Zusammenfassung Geomechanische Modelluntersuchungen für die Gründung von Talsperren Das Verhalten hoher bestehender Talsperren für Großspeicher, einige besondere Vorkommnisse bei der Nutzung derselben sowie einige Unfälle haben gezeigt, daß der Frage der Gründung von Talsperren besondere Bedeutung zukommt, da ein einwandfreies Zusammenwirken von Sperrenkörper und Gründungskörper für die potentiellen Lastfälle Voraussetzung für die Standsicherheit von Talsperren ist. Somit wird die Frage der Gründung von Talsperren bereits im Planungsstadium zu einem wesentlichen Bestandteil jeder ernsthaften Projektierung. Bei der Ausarbeitung von Alternativlösungen für den Talabschluß eines Speicherbeckens kann diese Frage sowie die Beurteilung des künftigen Verhaltens des Untergrundes der Sperre und des Speicherbeckens für die Dauer der vorgesehenen Nutzung die Wahl eines Sperrentyps maßgebend beeinflussen. Während wir für den Sperrenkörper mit Baustoffen arbeiten, deren Festigkeitsund Verformungseigenschaften wohlbekannt sind, ist dies für den Sperrenuntergrund, auch bei sorgfältig durchgeführten Voruntersuchungen und Aufschlußarbeiten während der Bauzeit nicht der Fall und auch nicht zu erwarten. Rechnerische und experimentelle Untersuchungen zur Erfassung des wahrscheinlichen Verhaltens des Untergrundes für ein Speicherbecken werden unter diesen Voraussetzungen in den meisten Fällen mit Schwierigkeiten behaftet sein; diese nehmen mit der Höhe der Talsperre als auch mit der Größe des Speicherraums zu. Die heute in der Talsperrenstatik üblichen Berechnungsmethoden, die das Untergrundverhalten in die Betrachtung mit einbeziehen, sind keineswegs so, daß sie als vollbefriedigend angesehen werden können. Über diese Tatsache kann auch der Einsatz von hochgezüchteten, für geomechanische Betrachtungen mehr oder weniger geeigneten Computerprogrammen beim Entwurf von Talsperren nicht hinwegtäuschen. Anhand von Prinzipskizzen von Talsperren verschiedener Typen wird die Frage der Kraftübertragung vom Sperrenkörper in den Untergrund im Zusammenhang mit den damit verbundenen Problemen erläutert, sowie auf die Grundzüge der bei der Planung von Sperren gebräuchlichen Berechnungsverfahren (mathematische Modelle) eingegangen. Der Aussagewert dieser Berechnungen im Hinblick auf die Beurteilung des Tragvermögens des Sperrenuntergrundes ist begrenzt und trägt — der Problemlösung inhärent — Zeichen einer ingenieurmäßig fundierten Abschätzung. Ein weiteres wertvolles Hilfsmittel für die Problemlösung steht dem planenden Ingenieur mit der Anwendung geomechanischer Modelluntersuchungen zur Verfügung. Bei Untersuchungen dieser Art werden das Gefügesystem (Groß- und Kleinklüfte) und Störungen im Felsuntergrund unter Berücksichtigung der Gefügeeigenschaften nachgebildet. In Abhängigkeit von den Anforderungen, dem Arbeitsaufwand und der angewandten Versuchstechnik wird die Qualität der Ergebnisse derartiger Untersuchungen sein. In vielen Fällen wird die Aussage nur qualitativen oder bestenfalls halb-quantitativen Charakter haben, jedoch in sehr anschaulicher Weise, z. B. potentielle gefährliche Verformungsvorgänge aufzeigen. Hauptsächlich dadurch sind sie ein wertvolles Hilfsmittel für den Entwurf, sowie für konstruktive und meßtechnische Entscheidungen. Je nach Aufgabenstellung werden derartige Versuche zweioder dreidimensional durchgeführt. Anhand einiger Beispiele werden die Einsatz- und Aussagemöglichkeiten von geomechanischen Versuchen erläutert, auf Entwicklungsmöglichkeiten bei der Anwendung sowohl für die Grundlagenforschung als auch für die projektbezogene Forschung wird hingewiesen. Abschließend wird festgestellt, daß die Bedeutung geomechanischer Untersuchungen in unserer Zeit des Computers nicht übersehen werden darf, da geeignete Berechnungsverfahren und adäquate Modelluntersuchungen als notwendige und gleichwertige, sich ergänzende Partner zu betrachten und heranzuziehen sind, um schwierige und verantwortungsvolle Entscheidungen bei der Errichtung von hohen Talsperren mit größtmöglicher Sicherheit treffen zu können; dies war grundsätzlich immer so, ist aber mit einer gewissen Euphorie der „allmächtigen“ Computer mancherorts in Vergessenheit geraten. Die Komplexität der Problemlösung einerseits und die der Verantwortung für ein einwandfreies Verhalten von Talsperren andererseits lassen die Notwendigkeit der Heranziehung aller bewährten Hilfsmittel zur bestmöglichen Erfassung der vielfältigen Aspekte der Problemstellung erkennen, um damit den Spielraum der Unsicherheiten in der Beurteilung der Standsicherheit einer Talsperre weitgehend einzuengen.

Notes: Summary The lower ultramafic part of the Chalkidiki Ophiolite Complex consists of a successive alternation of chromitite, dunite, and harzburgite, which is repeated periodically in a cyclic manner. This cyclic pattern is consistent with an origin as magmatic cumulates. However, the tectonic fabric superimposed on the cumulate texture of this sequence suggest a solid-state deformation at considerable depth. In the present study, the textural and chemical features of chromite are discussed. The interrelationships between the compositions of chromite, its mode of occurrence as well as the associated silicates are emphasized. It is found that the investigated chromites have properties in common with both podiforn and stratiform chromites. From a geometrical and structural point of view, they are of podiform type. On the other hand, their appreciably high iron content, the strong interdependence between the composition of chromite and the coexisting silicates together with the cryptic layering exhibited by the two mineral groups contrast markedly with podiform chromites. An alternative hypothesis is proposed involving fractional crystallization of an ultrabasic melt introduced to the magma chamber as periodic inflows of essentially the same composition. An upwelling upper-mantle that is subjected to stepwise partial fusion may fulfill these conditions.

Notes: Summary Au-and PGE-bearing samples1 from organogenic limestone located in the western part of the Lubin mine have been investigated. They contain: Au−Ag−Pt−Hg alloys, native Pd, sobolevskite (PdBi), native lead and plumbian gold which is related to an admixture of AuPb2, electrum (Ag2Au). Clausthalite also occurs in this association and contains up to 1% Ir. Kerogen is an important member of the association and contains, among others, 700 ppm Pt, 400 ppm Pd, 600 ppm Ir and 1100 ppm Au. These alloys are closely associated with nests of secondary calcite with dark brown internal reflections due to admixture of organic compounds. Organic matter colouring calcite II contains: ketones (chiefly diketones), nitrogen derivatives, phenols, probably tertiary alcohols and aromatic hydrocarbons. Metal carbonyls were also recorded. The organic substances investigated contain oxidation retarding derivatives.

Notes: Summary The mineral fibroferrite has the chemical formula Fe(OH)SO4·xH2O; the value forx has not been definitely settled, but as a rule it is found to be near five. Several symmetries are given in the literature. A sample from Saint Felix de Paillères, France, proved to be rhombohedral with space group R3; lattice constants for the hexagonal cell area=24.176,c=7.656 Å. As calculated from the experimental density (ρ=1.95 g·cm−3)Z=18 for this cell. Intensities were collected on an automated X-ray diffractometer from a thin fiber extended along [00.1]. The structure was determined by Patterson and Fourier methods. Least squares refinement with 818 observed reflections resulted inR=0.076. The structure contains hydroxo-bridged {Fe(OH)(H2O)2SO4} spiral chains built of [Fe(OH)2(H2O)2O2] octahedra and SO4 tetrahedra. Hydrogen bonds provide connections between these chains. The spiral chains are a stereoisomer variant of the hydroxo-bridged linear chains of Fe(OH)SO4, butlerite and parabutlerite. A comparison of these compounds is givenm to understand the relationship between the structure and their water content.

Notes: Zusammenfassung Die Kristallstruktur des Tunisits wurde zunächst an Material vom Originalfundort prinzipiell bestimmt; in Übereinstimmung mit einer neuen Analyse ergab sich eine Änderung der chemischen Idealformel auf NaCa2 Al4(CO3)4(OH)8Cl. Die Strukturverfeinerung erfolgte an dafür besser geeignetem Material aus Frankreich; mit 692 kristallographisch unabhängigen Röntgenreflexen wurde ein konventioneller ZuverlässigkeitsindexR=0,059 erreicht. Die Atomanordnung stellt einen neuen Strukturtyp mit [Al[6](OH)2 CO3]1−-Schichten parallel zu {001} dar. Die Na-Atome sind von vier O-Atomen und einem Cl-Atom koordiniert. Um die Ca-Atome wurde eine (4+2+4)-Koordination von Sauerstoffen gefunden; da sich für dieses Atom ein stark ausgelängtes Schwingungs-ellipsoid ergab, scheint eine Aufspaltung der Ca-Punktlage um ca. 0,4 Å möglich.

Notes: Zusammenfassung Der Grad der frühalpinen Metamorphose im Schneebergerzug und angrenzenden Altkristallin ist charakterisiert durch die beginnende Stabilität von posttektonisch gewachsenem Staurolith und Disthen am Nordrand des Schneebergerzuges. Das erste Auftreten von Staurolith ist durch erhöhten ZnO-Gehalt im Gestein kontrolliert, der im Staurolith mit maximal 5,6 Gew.% konzentriert ist. Erst südlich des Schneebergerzuges werden die Temperaturbedingungen der disk ontinuierlichen Mineralreaktion Granat + Chlorit + Muskovit = Staurolith + Biotit + Quarz + H2O überschritten. Die Staurolithbildung in paragonitreichen Schiefern wird der Mineralreaktion Paragonit + Chlorit + Quarz = = Staurolith + Albit + H2O zugeschrieben. Die häufige stabile Paragenese Paragonit + Quarz im chemisch reinen System limitiert die Maximaltemperaturen der frühalpinen Metamorphose mit einer thermodynamisch berechneten Temperatur von 570°C (5 kb). Mischkristallbildung, die im Albit stärker ist als im Paragonit und Verdünnung der Gasphase in Graphit-haltigen Gesteinen führte zur Instabilität von Paragonit und Quarz bei deutlich tieferen Temperaturen. Der Mg/Fe-Verteilungskoeffizient zwischen Granat und Biotit in bivarianten Paragenesen des Schneebergerzuges wird um einen Wert von 0,003 pro Mol.% Grossularkomponente im Granat erniedrigt. Die Verteilungskoeffizienten werden für diese Beeinflussung korrigiert und ergeben Gleichgewichtstemperaturen zwischen 548° und 577°C (5 kb). Eine weitere Erniedrigung des Verteilungskoeffizienten von Mg/Fe zwischen Granat und Biotit ist in Paragenesen mit zinkreichem Staurolith zu beobachten. Das Auftreten von Disthen läßt auf einen Mindestdruck während der frühalpinen Metamorphose von ∼5 kb bei 570°C schließen.

Notes: Summary Kutnohorite-quartz veins penetrate through a weakly metamorphosed Late Proterozoic sedimentary rhodochrosite carbonate in pyrite shales. Kutnohorite is pleochroic ranging from colourless (∈) to pinkish grey (ω), ω=1.735, ∈=1,543,d=3.066g·cm−3;a 0=4.852(1),c 0=16.219(7) Å. A quantitative chemical analysis leads to the formula (Ca0.95Mn0.05)1.00(Mn0.64Mg0.23Fe0.13)1.00(CO3)2.04. An electron microprobe scanning reveals considerable microscale inhomogeneity in cleavage rhombohedrons taken from a coarsely grained aggregate. It is mostly of the character of periodic fluctuations of the main element contents around an average value. There is a strong prevalence of an Fe+Ca−Mn+Mg antagonism, the extremes of compositonal differences lying in distances of 0.0X mm. The fluctuation maxima amount to about 9% for FeO, 6% for MnO, 3% for CaO, and 1.5% for MgO. In one of the samples even a two phase character with the above antagonism between the two phases was detected by X-rays. The inhomogeneities are due, partly at least, to the Fe-metasomatic processes that followed the formation of the kutnohorite by Alpine-paragenesis hydrothermal metamorphism.

Notes: Summary The crystal structure of låvenite (monoclinicP2 1 /a,a=10.83(1),b=9.98(1),c=7.174(5) Å, β=108.1(1)o), was refined using 1743 independent reflections toR=0.032 andR w=0.036. The refined structure is in agreement with the structure model proposed bySimonov andBelov (1960), characterized by the presence of walls of large cation polyhedra. These walls are four columns large, linked together by both direct connection as well as by Si2O7 groups. The cation distribution inside the wall is explained and compared with that found in other phase of the cuspidine group. The crystal chemical formula resulting from structural and chemical analyses on låvenite from Langesund (Norway) is (Na6.50Ca1.47Y0.03) (Ca0.93 Mn1.26Fe 0.87 2+ Ti0.65Zr0.18Mg0.05) (Zr3.42Nb0.58) (Si2O7)4O3.82F3.98.

Notes: Summary The Middle Proterozoic Faraday Metagabbro in the Bancroft area of eastern Ontario has been subjected to syn-orogenic textural and mineralogical modifications resulting in the formation of scapolite-bearing metagabbro and gabbroic blastomylonite assemblages. The elemental flux during cryptic and overt scapolitization has been calculated usingGresens general metasomatic equation which applies corrections for density and volume changes during alteration. Metasomatic variation diagrams using analyses from two primary gabbros and six altered rocks indicate that Na, K, Cl, Li, Rb, and Ba are the principal introduced elements and that Cu and S were removed. These changes are very similar to those involved in the formation of metasomatic nepheline-bearing rocks elsewhere in the district and, furthermore, nephelinization and scapolitization were broadly coincident in time and space. It is concluded that the nephelin- and scapolite-bearing rocks and their cryptic facies are different manifestations of the same metasomatic agent and that the source of the fluids was a possible horizon of evaporitic sediments within the country rocks in which the gabbro was emplaced.

Notes: Zusammenfassung An sieben Pegmatiten aus der Kor- und Saualpe wurden insgesamt 12 Rb−Sr-Gesamtgesteins-Analysen durchgeführt, an Muskoviten aus den Pegmatiten sind 16 Rb−Sr-Analysen und 15 K−Ar-Bestimmungen gemacht worden. Alle Pegmatite haben zwei Hellglimmergenerationen, die deutlich unterscheidbar sind. Mit der Rb−Sr-Methode ergeben die großen Muskovite (bis 20 cm ϕ) in acht Fällen praealpidische Alterswerte: 240 bis 265 M, J. Mit der gleichen Methode wird an den Muskoviten der zweiten Generation (bis 3 cm ϕ) alpidisches Alter bestimmt: 72 bis 122 M. J. Die Rb−Sr-Gesamtgesteins-Analysen deuten auf ein geöffnetes System für Rb−Sr in alpidischer Zeit, vergleichbar mit den Paragneisen (Morauf, 1980b). Die K−Ar-Bestimmungen an den Muskoviten beider Generationen ergeben alpidische Alterswerte; 71–116 M. J. Es ist ein Einfluß der Korngröße auf den Alterswert feststellbar sowie Unterschiede zwischen Kern und Rand bei den Muskoviten der ersten Generation. Prae-alpidische Mineral-Alter sind im Bereiche der Kor-und Saualpe nur noch in großen Pegmatit-Muskoviten nachweisbar, da durch eine altalpidische druckbetonte Metamorphose (vor 80 M. J.) nicht nur kleine Glimmer verjüngt/gebildet wurden, sondern auch die Gesamtgesteine zum teilweise offenen System für Rb und Sr wurden. Die prägende Deformation muß nach den vorliegenden Daten ebenfalls altalpidisch sein.

Notes: Summary This paper deals with some unsolved crystal chemical questions concerning a group of alkali iron hydrated sulphates based on clusters of composition [Fe 3 3+ O(SO4)6(H2O3]5− Taking the experimental chemical formulae, X-ray data and known crystal structures into account it is possible to establish the theoretical boundaries of the Na−K diadochy in metavoltine and also to define the influence of the Na−K replacement on the structure of α-Maus' salt. These considerations allow us to propose more general crystal chemical formulae, both for metavoltine and α-Mous' salt. Finally, the causes which affect the stability of metavoltine and α and β-Maus' salt are discussed.

Notes: Zusammenfassung Es werden die hydrothermalen Alterationen der subvulkanischen dazitischen Andesite-stellenweise mit Monzoniten und Monzodioriten vergesellschaftet — in einem Gebiet nördlich und nordöstlich von Kirki mineralogisch-petrographisch und chemisch untersucht und ihre Beziehungen zu den sulfidischen Vererzungen diskutiert. Sie werden schematisch wie folgt aufgeschlüsselt: 1. Eine hochthermale Alteration führte zur Bleichung und zu starken chemischen Veränderungen des Gesteins, das durch Albitisierung, Serizitisierung und Verkieselung gekennzeichnet ist. Hiermit ist eine Erzmineralisation des “porphyry-Typs” aus Molybdänit, Kupferkies und Pyrit verbunden. Um das gebleichte Gestein ist der dazitische Andesit propylitisiert. In diesem Umwandlungsstadium treten Chlorit, Epidot, Karbonate, Prehnit und Zeolith auf. 2. Nach der Intrusion des dazitischen Andesits erfolgte eine tektonische N−S bzw. NNW-SSE gerichtete Gangbildung, und es wurde die sulfidische Gangmineralisation, zunächst mit Sphalerit, eingeleitet. Die Hauptphase der Pb−Zn-Vererzung (Bleiglanz und Fe-freier Sphalerit und Wurtzit) fand jedoch im epi- bis telethermalen Stadium statt. Der gleiche Vulkanismus und ähnliche Alterationen sind auch in benachbarten Gebieten am SE-Rand der Rhodopen anzutreffen. Es wird insbesondere auf die Bedeutung der Bleichungshöfe und ihrer Erzmineralisation des “porphyry copper Typs” hingewiesen.

Notes: Summary The hydrogen content of 29 quartz crystals originating from the Penninic series of the central and western Tauern Window (Tyrol, Austria) was determined by IR spectroscopy. The hydrogen contents are between 7 and 66 H/106 Si-atoms. In one sample showing a mimetic lamellar structure H-contents up to 140 H/106 Si-atoms could be found. In most cases no difference exists between the hydrogen contents of margins and cores of the crystals. No clear relationships between the hydrogen content of the quartz lattice and the metamorphic temperature ranging from about 600°C to about 450°C can be found.

Notes: Summary Pressure/temperature estimates based on different combinations of calibrated mineralogical thermometers and barometers and alternative assumptions concerning the Fe2+/(Fe2++Fe3+) ratios in the mineral phases are compared for a suite of fourteen nodules. PreferredP/T values have been obtained by simultaneous solution of eq. (12) ofWood (1974) for garnet-orthopyroxene equilibria and theEllis andGreen (1979) equation defining theP,T,X dependence of the Fe2+−Mg2+ partition coefficient for coexisting garnet and clinopyroxene. However, to obtain realistic results it is first necessary to calculate the Fe3+ contents in the minerals—conveniently done on a charge balance basis. The favoured meanP/T estimates of 654±36°C and 10.8±3.1 kbs are compatible with a lower crustal origin for this nodule suite.

Notes: Summary Changes in morphology of the parent solid materials, and the texture of kaolin crystals developed during hydrothermal synthesis of kaolin, may be graphically followed by scanning electron micrography (SEM) of the samples drawn during synthesis. Because the chemical conditions prevailing during synthesis are controlled and known, a possiblity arises for correlating the type of kaolin texture that is produced with the various known properties of the genetic environment. In this study, which is a first attempt toward that objective, the texture of kaolin produced by four different variations of hydrothermal synthesis using amorphous silica, allophane, and gibbsite in H2SO4 and H4EDTA solutions are illustrated with SEMs. Elongate crystals of kaolin, and accordion-type mats of elongate crystals, not plates, interspersed with less dense layers of elongates are recorded.

Notes: Summary Thermal metamorphism and later retrogression of low metamorphic grade garnet-bearing pelites has produced diverse patterns of garnet zoning. In the narrow thermal aureole, fibrolite, staurolite and biotite are present and commonly are retrogressed to assemblages containing sericite, chlorite and chloritoid. In the thermal aureole, garnet contains inclusions of quartz, biotite, fibrolite, ilmenite, chlorite and muscovite and underwent relatively rapid growth from pre-existing low to medium grade regionally metamorphosed rocks. Garnet was armoured from breakdown reactions by fibrolite which nucleated on garnet. The grain size of poikiloblastic garnet, the volume of zones of inclusions in the garnet and the size of the inclusions all decrease with increasing distance from the contact. In the thermal aureole, normal compositional zoning is common and rare reversezoned garnets probably result from the partitioning of Mn from ilmenite during thermal metamorphism. Garnet grains in the thermal aureole have a peripheral enrichment in Mn in the outermost 200 μm as a result of diffusion of Fe from garnet into the matrix during incipient retrogression. Coarse retrograde garnet in schists is unzoned and richer in Fe than the normal- and reverse-zoned prograde garnet in hornfelses suggesting that relatively large scale local diffusion in retrograde schists was operative during retrogression but not effective enough to completely remove the relic prograde zoned garnets in the hornfelses.

Notes: Summary The green feldspar in alkali granite from the Avdar deposit of decoration stone (150 km W of Ulan-Bator) has been identified by means of physical and chemical methods as amazonite. Its structural state corresponds to that of microcline with a high degree of triclinicity and displaying the following anomalous dimensions of the unit cell (nm):a=0.8568,b=1.2967,c=0.7217 nm, α=90.732, β=115.851, γ=87.702°;V=0.72115 nm3. The amazonite contains in increased amount of Pb (1950 ppm) as well as of Rb (1.15 mass %). The genesis of this amazonite is associated with younger metasomatic processes in the alkali granite.

Notes: Summary Recently several natural and artificial ferric iron sulphate crystal structures have been solved. Sideronatrite, Na2Fe3+(SO4)2(OH)·3H2O, does not provide good crystals for structural purposes. However if we examine crystallographic, chemical and physical data some useful information about the ...Fe−O−S... structural topology can be inferred. In fact this analysis strengthens the hypothesis that there is a {Fe 2 3+ (SO4)4(OH)2} chain in sideronatrite like that found in guildite, Cu2+Fe3+(SO4)2(OH)·4H2O.

Notes: Zusammenfassung Die intermediären bis basischen Plutonite des Nördlichen Waldviertels aus dem Raum Gebharts-Pfaffenschlag werden petrologisch untersucht und ihre Genese sowie ihr möglicher Zusammenhang mit den großen granitischen Intrusionen dieses Bereiches diskutiert. Nach Mineralbestand und Chemismus können diese basischen Gesteine im Wesentlichen als Quarzmonzodiorite und Quarzmonzonite klassifiziert werden. Es wird gezeigt, daß diese Plutonite trotz variablem Chemismus einen weitgehend ähnlichen Entwicklungstrend aufweisen. Die Kristallisationsfolge beginnt je nach Ausgangschemismus mitOpx undKpx; mit steigendemP H2O erfolgte eine vollständige Uralitisierung der Pyroxene unter Bildung von Anthophyllit oder Mg- und Ca-Amphibolen. Der Abbau von Cummingtonit zu Biotit sowie die Verdrängung von Korund durch Margarit und die Bildung von Diaspor aus Spinell in Resorptionsschlieren spricht für eine langsame Abkühlrate unter kontrolliertenP H2O-Bedingungen. Die untersuchten dioritischen Gesteine werden aufgrund ihrer tieftemperierten Umwandlungsreaktionen als synorogene Intrusionen angesehen, wobei einP H2O ≃ 3 kb ≤P total bei einer angenommenen H2O-Sättigung der Schmelze einer Mindestintrusionstiefe von 12 km entspricht. Geochemisch sind die untersuchten Massengesteine anhand einiger Element-Quotienten von Krustenmaterial abzuleiten, wobei aber eine Beteiligung von Mantelmaterial nicht ganz ausgeschlossen werden kann. Die Haupt- und Spurenelementgehalte zeigen eine klare Entwicklungstendenz vom Gabbro von Kleinzwettl über Hornblende- und Biotitdiorite und Wolfsegger Granit bis zu den sauren Graniten vom Typus Schrems und Mauthausen und deren Ganggefolge. Daraus läßt sich ableiten, daß speziell die Diorite ein Produkt einer magmatischen Differentiation darstellen und gewissermaßen als basische Vorläufer der jüngeren Granite aufzufassen sind. Aufgrund von Tracht, Habitus und Wachstumstendenz der akzessorischen Zirkone ist allerdings eine direkte genetische Verwandtschaft zwischen den Dioriten (und dem Gabbro von Kleinzwettl) einerseits und den Graniten vom Typus Mauthausen, Schrems und Wolfsegg nicht anzunehmen. Tracht, Habitus und Einschlußtypen der Zirkone der basischen Gesteine schließen dagegen eine genetische Bindung zur Masse des Weinsberger Granites nicht aus. Trotz der sehr deutlichen geochemischen Entwicklungstendenz der untersuchten Massengesteine ist daher eine gewisse Eigenständigkeit der Magmenentwicklung der Diorite und deren gabbroider Vorläufer anzunehmen.

Notes: Summary The structure of hydrothermally synthesized cliffordite, approximate formula UTe3O9, space groupPa3-T h 6 ,a=11.335(5) Å was refined toR=0.053 with 501 independent three-dimensional diffractometer data. A full matrix least squares refinement yielded for one of the two U-positions a site occupancy factor of 0.82. A quantitative electronprobe microanalysis confirmed the corresponding U:Te ratio. A discussion of the charge balance is given. From reflectivity measurements the refractive indexn of cliffordite was determined to be 2.25(2) for λ=5890 Å.

Notes: Zusammenfassung Die Kristallstruktur des Minerals Teschemacherit, NH4CO2(OH), (a=7,255,b=10,709,c=8,746 Å;Z=8, Raumgruppe:Pccn) wurde an synthetischem Material mit 3-dimensionalen Röntgendaten verfeinert. Die Struktur wird aus parallel [001] verlaufenden [CO2(OH)]−-Ketten aufgebaut. Wasserstoffbrücken zu [NH4]+-Gruppen verbinden diese Ketten zu einem 3-dimensionalen Gerüst.

Notes: Summary The Habachtal emerald deposit, Hohe Tauern, is composed of blackwall sequences of the type: serpentinite — talc schist — ±chlorite schist or actinolite schist — biotite schist —albite gneiss and/or micaschist. 2 serpentinites, 33 blackwall rocks, 9 micaschists, 10 albite gneisses, and 5 aplitic gneisses were analyzed for major elements, and for Li, Be, Cr, Ni, Zn, Zr, Sn, in 36 samples also for Sc, Cu, Rb, Sr, Cs, Ba, W. The blackwall formation is due to a metasomatic exchange involving a transfer of Mg from the serpentinite to the silicic country rock, and of Si, Ca, K, and Al from the country rock to the serpentinite. Some of the trace elements were also mobile: Compared to serpentinite, Li and Be were enriched in all the blackwall rocks, and Sn and Cs in the actinolite, chlorite, and biotite schists; Sr was concentrated in the dolomite-bearing talc schists, and Zn, Rb, and Ba predominantly in the biotite schists.

Notes: Zusammenfassung Die chemische Analyse des neuenMMinerals Lammerit mit der Elektronenmikrosonde ergab: CuO 49,9, ZnO 0,8, MgO 0,2, FeO 0,2 und As2O5 49,8, Summe 100,9%. Aus diesem Ergebnis wurde die idealisierte Formel Cu3[AsO4]2 abgeleitet. Lammerit kristallisiert monoklin. Die möglichen Raumgruppen sindP21 oderP21/m. Die Gitterkonstanten sind:a=5,080(2),b=11,616(6),c=5,391(2) Å, β=111,71(3)°,Z=2. Die stärksten Linien des Pulverdiagramms sind: 4,06(5) ( $$11\bar 1$$ ), 3,80(6) (021), 3,06(8) (031), 3,00(8) (130), 2,89(10) (040, $$13\bar 1$$ ), 2,84(7) (111), 2,62(8) (121), 2.59(8) ( $$11\bar 2$$ ), 2,52(9) ( $$20\bar 1$$ , 041), 2,09(5) (150) und 1,582(6) ( $$25\bar 2$$ , 241). Lammerit ist dunkelgrün durchscheinend. Die Kristalle sind tafelig nach {100} und zu radialstrahligen Aggregaten verwachsen. Die Spaltbarkeit nach {010} ist ausgezeichnet, nach {100} gut und nach {001} angedeutet. Das Mineral ist optisch zweiachsig positiv, 2V∼54±5°. Die Werte der Lichtbrechung sind:n α≲1,89,n β=1,90 undn γ=1,95. Lammerit ist stark pleochroitisch mit den AchsenfarbenX=hellblau,Y=himmelblau undZ=bläulichgrün. Die Auslöschung istn α‖b und auf (010)n γ⋏c∼40°.H (Mohs)∼3,5–4.D=5,18 undD X =5,26 g·cm−3. Lammerit kommt gemeinsam mit Olivenit und einem weiteren vermutlich neuen Mineral vor. Der Fundort war Veta Negra. Laurani, Bolivien.

Notes: Summary A detailed electron microprobe study of the mineralogy of fifteen eclogites from the Moses Rock kimberlitic dyke, Utah, has demonstrated complexity in compositional zoning of minerals. Most of the eclogites examined are of the almandine-jadeite type and zonal and irregular variation in grossular content of garnet and acmite, jadeite and diopside-hedenbergite content of pyroxene produce large uncertainties in temperature estimates based on Fe/Mg partitioning between garnet and clinopyroxene. Zoning pattems of increasingX Mg in both clinopyroxene and garnet, and increasingX Jd in clinopyroxene, suggest the introduction of Mg and Na throughout the evolution of these essentially bimineralic assemblages. Averaged data yield temperatures from 340°C to 500°C at 10 kbar for compositions of rims of coexisting garnet and clinopyroxene. Two samples contain pyrope-rich gamets but coexisting pyroxenes are extremely magnesian and temperatures of equilibration of both primary omphacite-pyrope and secondary omphacite-almandine/pyrope-chlorite are only slightly higher (500–650° at 10 kbar) than those for almandine jadeite eclogites and estimates overlap with those of some examples of the latter type. Unlike the majority of almandine-jadeite eclogites, two examples contain garnets with almandine-cores and pyrope-rich rims without accompanying variation in grossular content. The simple interpretation of these samples as evidence of garnet growth during prograde metamorphism is precluded by complex zoning in coexisting clinopyroxene. The eclogites provide evidence for the presence of a metamorphic terrane including rocktypes resembling those of blueschist terranes beneath the Colorado Plateau but do not permit deduction of theP,T path by which such rocktypes reached theirP,TT-conditions (∼10 kbar, 400–600°C) of metamorphism.

Notes: Summary A meta-ironstone, composed essentially of eulite, almandine and quartz, and locally containing ferrifayalite (Fe4−x (SiO4)2), magnetite, clinopyroxene, biotite, graphite and plagioclase, was discovered at Louzi Mountain, Qianan, Eastern Hebei province, China. Its parent in terms of bulk rock chemistry is probably a Fe-rich sediment. The mineral chemistry and the distribution coefficient of Fe2+ and Mg between coexisting ferromagnesian minerals are defined, and also the inferared and Mössbauer spectra. According to the two-pyroxene geothermometers ofWood andBanno (1973),Saxena (1976), andWells (1977), the equilibrium crystallization temperature of the rock was about 750°C, and the pressure according toWood's method (1974) is about 13 kb at that temperature. It is implied that the rock has undergone granulite facies metamorphism.

Notes: Abstract The salic phases found in leucite-basanites, -trachytes, and -phonolites may be used to portray crystallization in the system NaAlSiO4-KAlSiO4-CaAl2Si2O8-SiO2, the phonolite pentahedron. Only two lavas have been found that contain the assemblage leucite-nepheline-plagioclase-sanidine and liquid, a natural pseudo-invariant assemblage (at 900° C±100) equivalent to the isobaric invariant point of the four component system. The diversity of phases in this group of lavas illustrates the role of halogens in controlling their crystallization paths. Thus the presence of F in the leucite-basanites has stabilized magnesian biotite and suppressed sanidine, as has been found in other basanitic lavas (Brown and Carmichael 1969). The presence of Cl in these same lavas has induced the crystallization of sodalite, which takes the place of nepheline in the groundmass. However in the leucite-trachytes, biotite has suppressed olivine and coexists with sanidine and leucite. The presence of S may produce haüyne at the expense of nepheline, and in general sulphate minerals, which include apatite, have the role in lavas of low silica activity that pyrrhotite plays in liquids of high silica activity. Both pyroxenes and titaniferous magnetites in this suite of lavas are very aluminous. Groundmass crystals of pyroxene may have one-fifth of Si replaced by Al. Other phases which occur occasionally are melanite garnet and a potassium-rich hastingsite, but neither ilmenite nor a sulphide mineral has been found. Phenocryst equilibration temperatures, derived from olivine and Sr-rich plagioclase, are generally in the range from 1,050° C to 1,150° C. The high content of incompatible elements (e.g., K, Ba, Rb, F, Sr, P) in these lavas suggests that they represent a small liquid fraction from a mantle source which possibly contains phlogopite.

Notes: Abstract New Sr isotopic data on lavas and xenoliths from Somma-Vesuvius and other nearby volcanic areas (Phlegrean Fields and Ischia) are presented. Chemical and isotopic evidences show that not all the Phlegrean Fields rocks belong to the low K series, but some of them may be interpreted as low pressure differentiates of Somma magmas, i.e. as a part of the high K series. Two rock groups are defined in the Ischia low K series, which are well identified both in time and in chemical and isotopic features, and cannot be derived from the same magma source. The low K series in the studied area generally has lower Sr isotopic values than the high K series. Historical Vesuvian lavas show two distinct linear trends with negative slopes when87Sr/86Sr ratios are plotted against their ages of eruption. Such trends are interpreted to result from mixing of magmas in two separate reservoirs. Evidence from the Vesuvian ejecta shows that Somma-Vesuvius magmas underwent high or low pressure fractionation, in connection with different events of the Vesuvian activity. Distinct magma reservoirs developed episodically at different depths. Isotopic and geochemical evidences do not favour large scale assimilation of crustal materials by Somma-Vesuvius magmas, but instead appear to reflect mantle characteristics. A minimum of three different (inhomogeneous) source regions is necessary to account for the isotopic features of the studied rocks.

Notes: Abstract The high-grade assemblage Cd-Ga-Si-Qz can be thermodynamically modelled from available calorimetric data on the metastable reaction: (I) $$3 MgCd \rightleftarrows 2 Py + 4 Si + 5 Qz$$ naturalK D Fe-Mg between garnet and cordierite and experimental results on cordierite hydration. In the system SiO2-Al2O3-MgO-H2O, reaction (I) becomes (II) $$3 MgCd \cdot nH_2 O \rightleftarrows 2 Py + 4 Si + 5 Qz + 3 nH_2 O$$ . However, hydrous cordierite is neither a hydrate nor a solid solution between water and anhydrous cordierite and when nH2O (number of moles of H2O in Cd) is plotted against $$P_{H_2 O} $$ , the resulting isotherms are similar to adsorption isotherms characteristic of zeolitic minerals. Reaction (II) can thus be considered as a combination of reaction (I) with a physical equilibrium of the type nH2O (in Cd)⇆nH2O (in vapor phase). Starting from a point on equilibrium (I), introduction of H2O into anhydrous Mg-cordierite lowers the chemical potential of MgCd and hence stabilizes this mineral to higher pressure relative to the right-hand assemblage in reaction (I). The pressure increment of stabilization,ΔP, above the pressure limit of anhydrous cordierite stability at constantT, has been calculated using the standard thermodynamics of adsorption isotherms. Cordierite is regarded as a mixture of Mg2Al4Si5O18 and H2O. The activity of H2O in the cordierite is evaluated relative to an hypothetical standard state extrapolated from infinite H2O dilution, by using measured hydration data. The activity of Mg2Al4Si5O18 in the cordierite is then obtained by integration of the Gibbs-Duhem equation, and the pressure stabilization increment,ΔP, computed by means of the relation: $$\Delta V_s \Delta P \cong - RT\ln a_{MgCd}^{MgCd \cdot nH2O} \left( {\Delta V indepentdent of P and T} \right)$$ . Thus, one may contour theP-T plane in isopleths of nH2O=constant within the area of Mg-cordierite stability allowed by the hydration data for $$P_{H_2 O} = P_{total} $$ . The present model indicates greater stabilization of cordierite by H2O than the model of Newton and Wood (1979) and the calculated curve for metastable breakdown of hydrous MgCd is consistent with experimental data on cordierite breakdown at $$P_{H_2 O} = P_{total} $$ . Mg/(Mg+Fe) isopleths have been derived for cordierites of varying nH2O in the SiO2-Al2O3-MgO-FeO-H2O system using the additional assumptions that (Fe, Mg) cordierite and (Fe, Mg) garnet behave as ideal solutions, and that typical values of the distribution coefficient of Fe and Mg between coexisting garnet and cordierite observed in natural parageneses can be applied to the calculations. The calculated stable breakdown curve of Fe-cordierite under conditions of $$P_{H_2 O} = P_{total} $$ to almandine, sillimanite, quartz and vapor has a positive slope (dP/dT) apparently in contrast to the experimental negative slope. This may be explained by hydration kinetics, which could have allowed systematic breakdown of cordierites of metastable hydration states in the experiments. The bivariant Cd-Ga fields calibrated from the present model are, potentially, good petrogenetic indicators, as, given the iron-magnesium ratio of garnet and cordierite and the hydration number of cordierite, the temperature, pressure and water fugacity are uniquely determined. As this geothermobarometer is in part based on the water content of cordierite, it can be used only if there is some assurance that the actual hydration is inherited from high-grade metamorphic conditions. Such conditions could be realised if the slope of unloading-cooling retrograde metamorphism is more or less parallel to a cordierite isohydron.

Notes: Abstract Petrographic, fluid inclusion, geochemical and isotopic evidence from xenoliths in alkali basalts suggests that low-viscosity fluids rich in O-H-C, dissolved silicates and especially the incompatible elements may ascend, decompress and precipitate crystalline phases and/or induce partial fusion in the upper mantle. Such mantle metasomatic fluids (MMF) may be important in generating isotopic heterogeneity and in transporting and focusing mantle heat. In order to model the movement of MMF, the ordinary differential equations governing the variation ofP, T, ascent velocity and fluid density of a compressible, viscous, single-phase (H2O or CO2) non-reacting fluid ascending through a vertical crack of constant width have been solved. A large number of numerical simulations were carried out in which the significant factors affecting flow behavior (thermodynamic and transport fluid properties, roughness and width of cracks, geothermal gradient, initial conditions, etc.) were systematically varied. The calculations show that: (1) MMF tends to move at uniform rates following a short period of rapid initial acceleration, (2) MMF ascends nearly isothermally, (3) MMF acts as an efficient heat transfer agent; numerical experiments show that transport of heat into regions undergoing metasomatism can lead to partial fusion. The heat transported by movement of MMF averaged over the age of the Earth is sufficient to generate about 0.1 km3 of basaltic magma per year, which is approximately equal to the production rate of alkaline magma. If an intense period of mantle degassing occured early in the history of the Earth, the transport of heat and mass (K, U, Rb, LREE) by migrating fluids might have been important.

Notes: Abstract Quaternary alkali olivine basalts and nephelinites from the Hoggar area (Southern Algeria) contain numerous lherzolite inclusions. The investigated nodules have been classified into three textural categories: coarse, porphyroclastic and granuloblastic. Microprobe analyses have been carried out on the coexisting phases (olivine, clinopyroxene, orthopyroxene, spinel, pargasite, Al rich glass) from 10 selected samples, with a special attention to pyroxene porphyroclasts which are zoned in Al and Cr. Most of the porphyroclastic xenoliths contain secondary pargasite (or its breakdown products) which is thought to reflect a metasomatic event in mantle conditions. Equilibrium temperatures and pressures have been calculated for the three groups, using the single-pyroxene method: the coarse samples have been equilibrated at higher pressures (20–25 kb) and temperatures (1,000° C–1,100° C) than the granuloblastic samples (about 10 kb and 900° C); with regards to the porphyroclastic xenoliths, the estimated T and P have been related to two stages of crystallization (corresponding to porphyroclasts and neoblasts). Relationships between phase compositions, rock-textures and metasomatism are briefly discussed.

Notes: Abstract Stabilities of amphibole and chlorite in mafic and ultramafic compositions have been considered in the model system CaO+MgO+Al2O3+SiO2+H2O. From topological arguments two petrogenetic grids have been constructed. Although available experimental data in CMASH are compatible with the grid in which amphibole reacts out before chlorite in model ultramafic compositions for the pressure range 6 to 15 kbar, naturally observed mineral assemblages and some experimental data in more complex systems favour the other grid in which chlorite reacts out before amphibole at all pressures. This discrepancy between natural and model systems is due to differential movement of the dehydration equilibria of the two hydrates reflecting the variation of activity of H2O or of components other than CMASH.

Notes: Abstract Along a NW-SE profile through the basement core, starting below the sedimentary unconformity and ending in the center of the nearly circular structure, the constituent quartz grains and their fluid inclusions exhibit the following characteristics: In the NW, fluid inclusions composed of CO2 and occasionally up to 50 Vol.% H2O occur along shock-induced planar elements following predominently {0 0 0 1} of coarse, largely unrecrystallized quartz grains. The planar elements are partly still open microcracks, partly they are healed, the fluid inclusions decorating the former sites of the cracks. Along these planar elements recrystallization into fine grained new quartz fabrics starts, this process increasing decidedly towards the southeast; nevertheless fluid inclusions are still retained. — Near and within the center of the dome the formerly coarse quartz grains are completely recrystallized to medium grained annealing fabrics, in which — surprizingly — the fluid inclusions have often retained their original positions relative to the old grains, so that their planar alignment now traverses the new grain boundaries. Here the enclosed fluid is pure CO2 as far as can be determined. On the basis of the homogenization temperatures of the fluid inclusions measured, and of independent petrologic geothermometry of the basement rocks near the center, the fluids trapped after the shock event had exhibited partial pressures of CO2 as high as 3 kbars at temperatures around 850° C. The derivation of these CO2-rich, post-shock fluids is either through release of older fluid inclusions from the lower crustal granulites affected by the catastrophic shattering event, or it is from a direct mantle source that might be genetically connected with the Vredefort event itself.

Notes: Abstract Plagiogranites in the Canyon Mountain ophiolite, Oregon, include a wide range of rock types ranging from diorite to trondhjemite. The plagiogranites are mostly concentrated as an intrusive sill swarm at the top of a section of gabbroic cumulates. The plagiogranites are typically low in K2O and high in Na2O, and are enriched 10–20 times chondrites in REE, and overlap with abundances in basic rocks from Canyon Mountain. All samples of plagiogranite are relatively depleted in LREE, with more silicic samples characterized by a slightly lesser degree of LREE depletion. Total REE content is not consistently correlated with contents of major and other trace elements. Fractional crystallization of basaltic magma may give rise to plagiogranites; however this model applied to Canyon Mountain plagiogranites is discounted because of the significant volume of plagiogranites relative to basic rocks, and the complete overlap of REE abundances of the basic rocks and the plagiogranites. The latter is also a major reason for rejecting the hypothesis of silicate liquid immiscibility in the generation of the plagiogranites. Field observations coupled with major-element and trace element chemistry lend support to a model by which the plagiogranites were produced by partial melting of basic rocks under hydrous conditions. REE data for the plagiogranites were used in calculations to delimit source REE contents. Relevant parameters in the calculations were estimated from experimentally determined phase relations of basalt under hydrous conditions. The resulting calculated source patterns are similar to those of basic rocks in ophiolites and oceanic settings, and suggest boundary conditions for the model. Partial melting as suggested for the Canyon Mountain plagiogranites probably occurred at relatively shallow depths (i.e., total pressures less than 5 kb).

Notes: Abstract Green, salitic pyroxenes occur as megacrysts and as cores in diopsidic pyroxene phenocrysts and microphenocrysts in a wyomingite lava from Hatcher Mesa, Leucite Hills, Wyoming. Al-rich phlogopite (16–21% Al2O3), apatite, Fe-Ti-oxide, Mg-rich olivine (Fo93) and orthopyroxene (En61) also occur as megacrysts or as inclusions in diopside phenocrysts. All of these phases are found in ultramafic xenoliths in the host lava, and petrographic and chemical evidence is presented that the megacrysts originate by the disaggregation of the xenoliths. It is concluded that the latter are accidental fragments of the wall rocks traversed by the wyomingite magma and it is suggested that the clinopyroxene-rich xenoliths, from which the green pyroxenes are derived, formed in the upper mantle as a result of local metasomatism or by crystallization from magmas of unknown composition during an earlier igneous event. The precise role of the clinopyroxene-rich xenoliths (which also contain apatite, Fe-Ti-oxide and amphibole) in the genesis of the Leucite Hills magmas cannot be elucidated on the basis of the available data, but it is unlikely that they represent the source material from which these magmas are derived.

Notes: Abstract Samples of a garnet granulite from the mafic border units of the Lake Chatuge, Georgia alpine peridotite body were found to contain lamellar intergrowths of a pargastic amphibole in augite having the typical appearance of an exsolution feature. Single crystal X-ray diffraction, optical, electron microprobe and conventional and analytical electron microscopic studies have provided data limiting the compositions and structures of the coexisting phases. Individual lamellae of both materials are from 0.5 to 2.0 μm in width with the lamellar interface parallel to {0 1 0}. The formulae of the minerals, as determined by a combination of electron microprobe and analytical electron microscopy, are (Na0.1Ca1.0Mg0.6Fe3+ 0.3)(Si1.8Al0.2)O6 for the pyroxene and Na0.7Ca1.9(Mg2.1Fe2+ 1.4Fe3+ 0.5Ti0.1Cr0.1Al0.8)(Si5.9Al2.1) O22(OH)2 for the amphibole. Several other studies have described intergrowths similar to those observed in this work, in general favoring exsolution as the formation mechanism for the intergrowths. In the Lake Chatuge samples however, replacement of pyroxene by amphibole is in part indicated by continuous gradation of amphibole lamellae into amphiboles rimming the clinopyroxenes.

Notes: Abstract Mineral assemblages, rock and mineral chemistry, and mineral reactions, in calc-silicate rocks from Koduru area, Andhra Pradesh, India are discussed. Mineralogical and bulk chemical differences indicate 3 calc-silicate rock types — type I with K feldspar+calcite+wollastonite+quartz+scapolite+diopsidess +andraditess+sphene, has relatively high rock oxidation ratios. Type II is a highly calcic variety with high rock Mg∶Fe ratios, and has K feldspar+calcite+wollastonite+quartz+scapolite + diopsidess±grossularitess+sphene+zoisite. Type III has K feldspar +calcite+wollastonite+quartz+scapolite+diopsidess +sphene+hornblende+magnetite, and has relatively low oxidation ratio and low Mg∶Fe ratio. The 3 calc-silicate rock types have originated as mixtures of limestone/dolomite/marl. Diopside was produced by a reaction involving Ca-amphibole +calcite+quartz, and reversed during retrogression. Andraditess in type I rocks was produced at the expense of hedenbergitic component of pyroxene in a continuous reaction as a consequence of increase in the oxygen content of the original sediment relative to type III. Calcite+quartz reacted to give wollastonite. During cooling an influx of water caused scapolite to alter to zoisite.

Notes: Abstract δ 18O and87Sr/86Sr isotopic data from smectites, calcites, and whole rocks, together with published isotopic age determinations, alkali element concentration data and petrographic observations suggest a sequential model of ocean floor alteration. The early stage lasts about 3 m.y. and is characterized by palagonite and smectite formation, and solutions with a large basaltic component, increasing with temperature which varies from 15° to 80° C at DSDP site 418A. Most carbonates are depositedafter this stage from solutions with a negligible basaltic Sr component and temperatures of 15° to 40° C. Water of seawater Sr and O isotopic composition is shown to percolate to at least 500 m into the basaltic basement. No evidence was found for continuing exchange of strontium or oxygen after 3 m.y.

Notes: Abstract The stability of coexisting orthopyroxene, sillimanite and quartz and the composition of orthopyroxene in this assemblage has been determined in the system MgO-FeO-Fe2O3-Al2O3-SiO2-H2O as a function of pressure, mainly at 1,000° C, and at oxygen fugacities defined mostly by the hematite-magnetite buffer. The upper stability of the assemblage is terminated at 17 kbars, 1,000° C, by the reaction opx+Al-silicate →gar+qz, proceeding toward lower pressures with increasing Fe/(Fe+Mg) ratio in the system. The lower stability is controlled by the reaction opx+sill+qz→ cord, which occurs at 11 kbars in the iron-free system but is lowered to 9 kbars with increasing Fe/(Fe+Mg). Spinel solid solutions are stabilized, besides quartz, up to 14 kbars in favour of garnet in the iron-rich part of the system (Fe/(Fe+Mg)≧0.30). Ferric-ferrous ratios in orthopyroxene are increasing with increasing ferro-magnesian ratio. At least part of the generally observed increase in Al content with Fe2+ in orthopyroxene is not due to an increased solubility of the MgAlAlSiO6 component but rather of a MgFe3+AlSiO6 component. The data permit an estimate of oxygen fugacity from the composition of orthopyroxene in coexistence with sillimanite and quartz.

Notes: Abstract The late Pleistocene caldera complex of the Sierra La Primavera, Jalisco, México, contains well-exposed lava flows and domes, ash-flow tuff, air-fall pumice, and caldera-lake sediments. All eruptive units are high-silica rhyolites, but systematic chemical differences correlate with age and eruptive mode. The caldera-producing unit, the 45-km3 Tala Tuff, is zoned from a mildly peralkaline first-erupted portion enriched in Na, Rb, Cs, Cl, F, Zn, Y, Zr, Hf, Ta, Nb, Sb, HREE, Pb, Th, and U to a metaluminous last-erupted part enriched in K, LREE, Sc, and Ti; Al, Ca, Mg, Mn, Fe, and Eu are constant within analytical errors. The earliest post-caldera lava, the south-central dome, is nearly identical to the last-erupted portion of the Tala Tuff, whereas the slightly younger north-central dome is chemically transitional from the south-central dome to later, moremafic, ring domes. This sequence of ash-flow tuff and domes represents the tapping of progressively deeper levels of a zoned magma chamber 95,000 ± 5,000 years ago. Since that time, the lavas that erupted 75,000, 60,000, and 30,000 years ago have become decreasingly peralkaline and progressively enriched only in Si, Rb, Cs, and possibly U. They represent successive eruption of the uppermost magma in the post-95,000-year magma chamber. Eruptive units of La Primavera are either aphyric or contain up to 15% phenocrysts of sodic sanidine ≧quartz 〉ferrohedenbergite 〉fayalite〉ilmenite±titanomagnetite. Whereas major-element compositions of sanidine, clinopyroxene, and fayalite phenocrysts changed only slightly between eruptive groups, concentrations of many trace elements changed by factors of 5 to 10, resulting in crystal/glass partition coefficients that differ by factors of up to 20 between successively erupted units. The extreme variations in partitioning behavior are attributed to small changes in bulk composition of the melt because major-element compositions of the phenocrysts and temperature, pressure, and oxygen fugacity of the magma all remained essentially constant. Crystal settling and incremental partial melting by themselves appear incapable of producing either the chemical gradients within the Tala Tuff magma chamber or the trends with time in the post-caldera lavas. Transport of trace metals as volatile complexes within the thermal and gravitational gradient in volatilerich but water-undersaturated magma is considered the dominant process responsible for compositional zonation in the Tala Tuff. The evolution of the post-caldera lavas with time is thought to involve the diffusive emigration of trace elements from a relatively dry magma as a decreasing proportion of network modifiers and/or a decreasing concentration of complexing ligands progressively reduced trace-metal-site availability in the silicate melt.

Notes: Abstract The hydration of peridotites modelled by the system H2O-CaO-MgO-Al2O3-SiO2 has been treated theoretically after the method of Schreinemakers, and has been investigated experimentally in the temperature range 700°–900° C and in the pressure range of 8–14 kbar. In the presence of excess forsterite and water, the garnet- to spinel-peridotite transition boundary intersects the chlorite dehydration boundary at an invariant point situated at 865±5° C and 15.2±0.3 kbar. At lower pressures, a model spinel lherzolite hydrates to both chlorite- and amphibole-bearing assemblages at an invariant point located at 825±10° C and 9.3±0.5 kbar. At even lower pressures the spinel-to plagioclase-peridotite transition boundary intersects the dehydration curve for amphibole+forsterite at an invariant point estimated to lie at 855±10° C and 6.5±0.5 kbar. Both chlorite and amphibole were characterized along their respective dehydration curves. Chlorite was found to shift continuously from clinochlore, with increasing temperature, to more aluminous compositions. Amphibole was found to be tremolitic with a maximmum of 6 wt.% Al2O3. The experimentally determined curves in this study were combined with the determined or estimated stability curves for hydrous melting, plagioclase, talc, anthophyllite, and antigorite to obtain a petrogenetic grid applicable to peridotites, modelled by the system H2O-CaO-MgO-Al2O3-SiO2, that covers a wide range of geological conditions. Direct applications of this grid, although quite limited, can be made for ultramafic assemblages that have been extensively re-equilibrated at greenschist to amphibolite facies metamorphism and for some highgrade ultramafic assemblages that display clear signs of retrogressive metamorphism.

Notes: Abstract The equilibrium between spinel lherzolite and garnet lherzolite has been experimentally determined in the CaO-MgO-Al2O3-SiO2 system between 800° and 1,100° C. In confirmation of earlier work and predictions from thermodynamic data, it was found that theP-T slope of the reaction was close to zero, the equilibrium ranging from 16.1 kb at 800° C to 18.7 kb at 1,100° C (±0.3 kb). The addition of Cr2O3 to the system raised the stability field of spinel to higher pressures. It was found that the pressure at which both garnet and spinel could exist with olivine+orthopyroxene+clinopyroxene in the system CMAS −Cr2O3 could best be described by the empirical relationship: $$P = P^{\text{O}} + \alpha X_{{\text{Cr}}}^{s{\text{p}}} $$ whereP 0 is the equilibrium pressure for the univariant reaction in the Cr2O3-free system,α is a constant apparently independent of temperature with a value of 27.9 kilobars, andX Cr sp is the mole fraction of chromium in spinel. Use was made of the extensive literature on Mg-Fe2+ solid solutions to quantitatively derive the effect of Fe2+ on the equilibrium. The effect of other components (Fe3+, Na) was also considered. The equilibrium can be used as a sensitive geobarometer for rocks containing the five phases ol+opx+cpx+gt+sp, and thus provides the only independent check presently available for the more widely applicable geobarometer which uses the alumina content of orthopyroxene in equilibrium with garnet.

Notes: Abstract A dacite sample from a nuée ardente deposit at Pitons du Carbet, Martinique, contained cummingtonite, orthopyroxene, quartz, magnetite, and ilmenite as phenocrysts, and thus was suitable for evaluation of the $$T - f_{{\text{O}}_{\text{2}} } - P_{{\text{total}}} - P_{{\text{H}}_{\text{2}} {\text{O}}} $$ conditions of crystallization of nuée ardente materials according to the method of Ewart et al. (1971). The estimations were obtained with the aid of a Fortran IV program, which permitted the operation of all the arrangements between the available microprobe analyses. The results indicated that the phenocrystic association crystallized at moderate temperatures (ca. 750° C), under high oxygen fugacities (〉 NNO) and total pressures (2.3–4.5 Kb, with a maximal density of points at about 3.5 Kb), and water pressures approximating total pressures. The groundmass Fe-Ti oxides equilibrated at lower temperatures and under relatively increasing oxygen fugacities, the variation of which is tentatively ascribed to the aerial emplacement of the nuée ardente materials. The phenocryst data imply that in the case studied the high fluid pressures characterizing the nuée ardente eruptions were not acquired at a shallow level because of the deep intratelluric stage of crystallization of these differentiated calcalkalic magmas.

Notes: Abstract Curved, layered objects in a subalkaline, potassic, intrusive granite are analyzed: biotite laminae and cyclic reverse size and modal layers are encountered in an annular zone; both cyclic and intermittent layers are observed in rhythmic arrangement. Truncation, the bifurcation curvature of layers with ladle shape, represents the action of magmatic currents, as would convection cells or fluid-dynamic fingers. Emphasis is put on the Bagnold effect related to such currents, which would explain the reverse size-grading of layers; this kind of size-sorting (hydrodynamic) occurs in highly viscous granitic magma. Simple convection seems more likely than diffusive convection.

Notes: Abstract Trace element evidence indicates that at the Buell Park diatreme, Navajo volcanic field, the felsic minette can be best explained by crystal fractionation from a potassic magma similar in composition to the mafic minettes. Compatible trace element (Cr, Ni, Sc) abundances decrease while concentrations of most incompatible elements (Ce, Yb, Rb, Ba, Sr) remain constant or increase from mafic to felsic minette. In particular, the nearly constant Ce/Yb ratio of the minettes combined with the decrease in Cr, Ni, and Sc abundances from mafic to felsic minette is inconsistent with a model of varying amounts of partial melting as the process to explain minette compositions. The uniformity of rare earth element (REE) abundances in all the minettes requires that an accessory mineral, apatite, dominated the geochemistry of the REE during fractionation. A decrease in P2O5 from mafic to felsic minette and the presence of apatite in cognate inclusions are also consistent with apatite fractionation. Higher initial87Sr/86Sr ratios in the felsic minettes relative to the proposed parental mafic minettes, however, is inconsistent with a simple fractionation model. Also, a separated phlogopite has a higher initial87Sr/86Sr ratio than host minette. These anomalous isotopic features probably reflect interaction of minette magma with crust. The associated ultramafic breccia at Buell Park is one of the Navajo kimberlites, but REE concentrations of the matrix do not support the kimberlite classification. Although the matrix of the breccia is enriched in the light REE relative to chondrites, and has high La, Rb, Ba, and Sr concentrations relative to peridotites, the concentrations of these elements are significantly lower than in South African kimberlites. A high initial87Sr/86Sr ratio combined with petrographic evidence of ubiquitous crustal xenoliths in the Navajo kimberlites suggests that the relatively high incompatible element concentrations are due to a crustal component. Apparently, Navajo kimberlites are most likely a mixture of comminuted mantle wall rock and crustal material; there is no evidence for an incompatible element-rich magma which is characteristic of South African kimberlites. If the mafic minettes are primary magmas derived from a garnet peridotite source with chondritic REE abundances, then REE geochemistry requires very small (less than 1%) degrees of melting to explain the minettes. Alternatively, the minettes could have formed by a larger degree of melting of a metasomatized, relatively light REE-enriched garnet peridotite. The important role of phlogopite and apatite in the differentiation of the minettes supports this latter hypothesis.

Notes: Abstract Native iron-bearing strongly sediment-contaminated andesitic to dacitic lavas from the Maligât Formation on Disko contain an early phenocryst assemblage of plagioclase, low-Ca pyroxene(s) and ilmenite. The phenocrystic ilmenite has reacted to form complex Fe-Ti oxide-metal-sulphide aggregates, which contain one or more of the oxides ilmenite, armalcolite and rutile. The armalcolite is very similar to the lunar type 1 armalcolite of Haggerty (1973) and approximate compositionally the ternary system FeTi2O5-MgTi2O5-Ti3O5 (92 to 97 mol.%). When evidence from several salic rocks is combined the Fe-Ti oxide-metal-sulphide aggregates display reactions which may represent one isobaric invariant assemblage (ilmenite-armalcolite-rutile-iron) and the 3 boundary univariant reactions in the system Fe-Ti-O. The compositional and textural features of ferro-magnesian silicates, oxides and metals show that most rocks were affected by a rapidly declining f O 2 during magma ascent and cooling, as displayed in the Fe-Ti oxide-metal-sulphide aggregates by the cross-cutting of one or several T—f O 2 buffer curves in the system Fe-Ti-O. Prominent sulphidation reactions are observed in the oxide aggregates and are always of the type where FeO in oxide is replaced by FeS while the liberated oxygen is consumed in a reduction process. Carbon, bound as graphite or cohenite, occurs throughout the rocks and is mostly enclosed in phenocrysts and xenocrysts. When the salic magmas ascended from pre-eruption reservoirs at 1 to 1.5 kb the reduction was largely controlled by strongly pressure-dependent carbon-oxygen equilibria resulting in rapidly declining T—f O 2 paths recorded by the oxide assemblages. In the simplified C-O gas system carbon-barometry (Sato 1979) applied to the selected rocks would indicate final equilibrium pressures of between 10 and 100 bars. The scarcity of preserved graphite in the lavas would suggest that the carbon-controlled reductions were terminated when available carbon was exhausted during the magma ascent and solidification.

Notes: Abstract Flux-grown crystals of Mg-cordierite, Mg1.93 Al3.95 Si5.07 O18 synthesized by Lee and Pentecost (1976) appear biaxial (2V x=10°–25°) under the polarizing microscope whereas their distortion index Δ=0°. Between crossed polars, (001) sections display lamellar and cyclic twinning on {110} and, less frequently, {310}. As duration of annealing at 1,300° C, increased, 2V x increased. Simultaneously, undulatory extinction and intragrain variations in 2V x increased slightly up to 4 h annealing, then steadily decreased. For this Mg-cordierite, which lacks significant channel H2O or CO2, 2V x and Δ reach maxima of 88° (λ=589 nm) and 0.25° after 42 h of annealing but other sectors still display lesser values for 2V x. Presumably, to the extent 2V x is less than 88°, these sectors represent intergrown submicros copically twinned orthorhombic domains and thus possess shortrange but not long-range order. Annealing at 1,300° C likely increased long-range order by promoting growth of larger domains at the expense of smaller ones. Ultimately, two differently oriented domains, growing toward each other by annexation (and re-orientation) of smaller domains, meet in a twin boundary that, with time, tends to become straight. The cause of intermediate values for Δ, whether compositional or from submicroscopic {110} or {310} twinning, may be revealed by single crystal X-ray photographs. Streaking of diffraction spots along a* or b* (but not c*) will indicate such twinning as the sole or major cause.

Notes: Abstract Equilibria between plagioclase, calcic amphibole and quartz can be described, in part, by the relation among mineral components: NaAlSi3O8+□Ca2Mg5Si8O22(OH)2 = NaCa2Mg5AlSi7O22(OH)2+4SiO2; this relation governs the partitioning of Na between plagioclase and the A-site of coexisting amphibole. Data from natural amphibolites reveal that this partitioning is systematic and sensitive to metamorphic grade. The ideal portion of the equilibrium constant (K id = X Na, A/X□, A · X Ab) derived from natural samples is sensitive to bulk composition, inasmuch as both plagioclase and amphibole are highly non-ideal. Samples from a single outcrop have values ranging from 0.5 (X Ab=0.74) to 4.1 (X Ab=0.10). The continuous reaction, NaAlSi3O8+□Ca2Mg5Si8O22(OH)2 = NaCa2Mg5AlSi7O22(OH)2+4SiO2, proceeds to the right with increasing grade of metamorphism and for a given bulk composition, K id increases with increasing temperature. Two related discontinuous reactions, actinolite+albite=hornblende+oligoclase+quartz and actinolite+oligoclase=hornblende+anorthite+quartz, also proceed to the right with increasing metamorphic grade and result in changes in the topology of a phase diagram that describes the partitioning of Na between plagioclase and amphibole A-site. A Schreinemakers' net is presented that is consistent with natural occurrences. The results of this study should aid in the delineation of metamorphic facies within amphibolites.

Notes: Abstract Isotopic studies of rocks from oceanic island arcs such as the Marianas indicate that little, if any, recycling of continental material (e.g. oceanic sediments) occurs in these arcs. Because oceanic arcs are on the average more mafic than the dominantly andesitic continental arcs, an important question is whether the andesites of continental arcs are produced by a fundamentally different (more complex?) mechanism than the lavas of oceanic arcs. An excellent opportunity for study of this question is provided by the island of Sarigan, in the Mariana active arc, on which calc-alkaline andesites (including hornblende-bearing types) are exposed along with more mafic lavas. Available isotope data suggest the Sarigan lavas (including the andesites) were derived from mantle material with little or no involvement of continental components. Ratios of incompatible elements suggest that most of the Sarigan lavas were derived from similar source materials. Absolute abundances of incompatible elements vary irregularly within the eruptive sequence and indicate at least 5 distinct magma batches are represented on Sarigan. Major element data obtained on the lavas and mineral phases in them, combined with modal mineral abundances, suggest that the calc-alkaline nature of the volcanic rocks on Sarigan results from the fractional crystallization of titanomagnetite in combination with other anhydrous phases. Amphibole, although present in some samples, is mainly a late-crystallizing phase and did not produce the calc-alkline characteristics of these lavas. Gabbroic samples found in the volcanic sequence have mineralogc and geochemical characteristics that would be expected of residual solids produced during fractional crystallization of the Sarigan lavas. When combined, data on the lavas and the gabbros suggest the following crystallization sequence: olivine — plagioclase — clinopyroxene — titanomagnetite — orthopyroxene±hornblende, biotite and accessory phases. These results lead to the conclusion that calc-alkaline magmas can be generated directly from mantle sources.

Notes: Abstract A scapolite+amphibole+clinopyroxene+Fe-Ti oxide+apatite association has been found as megacrysts in tephra from the Enval-Volvic volcanic line, east of the Chaîne des Puys (Massif Central, France) and in the cinder cone of the Segueïka volcano (Atakor, Algeria). In both kinds, lavahosts are basanites. Although never seen together in a single xenolith, a study of their inclusions indicates close genetic relationship between all 5 phases. This association must be considered as a paragenesis that crystallized within a narrow PT range. Volcanological, petrological and geochemical data suggest that these megacrysts are high-pressure phenocrysts rather than mechanically desintegrated fragments derived from coarse rocks. The composition of the amphibole suggests a pressure between 5 and 15 kb; Fe-Ti oxides imply a temperature close to 1,100° C. Crystallization of sulfur-rich scapolite involves a high fSO3, and therefore a high fO2, remarkable for such relatively undifferenciated alkalic magmas. Coexisting Fe-Ti oxides indicate a fO2 close to 10−6 bar. Such conditions imply that H2O was a major component of the gaseous phase. This high water content can be explained in terms of derivation from an hydrated upper mantle source. This is in agreement with other petrological evidences indicating that the basic magmas of the Massif Central crystallized under high fSO3 conditions.

Notes: Abstract Cretaceous alkaline intrusive rocks present in the Bitterfontein area comprise a suite having compositions ranging from olivine melilitite to syenite. These rocks which include some of lamprophyric affinity form part of the widespread dominantly alkaline suite of intrusives occurring in a broad zone parallel to the south western African coastal regions. This paper presents the petrology of the Bitterfontein alkaline rocks together with mineral and rock analyses. The chemistry of the rocks shows the suite to define a SiO2 enrichment trend linking the compositions of olivine melilitite to oversaturated basic rocks. This trend is compared with trends defined by essentially tholeiitic volcanics and kimberlite-olivine melilitite compositions and a genetic relationship with the latter is apparent. Polybaric crystallisation of a larnite normative liquid in a crustal environment coupled with fractionation especially of phlogopite is important in the generation of members of the Bitterfontein suite. Phlogopite fractionation represents a deviation by the Bitterfontein suite from the evolutionary trend predicted by experimental work for low pressure anhydrous compositions in the Fo-La-Ne-SiO2 system.

Notes: Abstract Microphenocrystic pyrrhotites were observed in the glassy groundmass of two dacite rocks from Satsuma-Iwojima, southwest Kyushu, Japan. It suggests that the dacite magma was saturated with respect to pyrrhotite at the time of eruption, and thus the sulfur contents in the groundmass can be taken as the solubility of sulfur in the dacite magma. The solubility of sulfur in the dacite rocks thus calculated is 65 to 72 ppm sulfur at the estimated conditions of T=900±50°C, $$f_{{\text{O}}_{\text{2}} } = 10^{ - 12 \pm 1}$$ and $$f_{{\text{S}}_{\text{2}} } = 10^{ - 0.6 \pm 0.6}$$ atm.

Notes: Abstract Clasts of shocked garnet-sillimanite gneisses comprise a minor fraction of the allochthonous breccia at the Haughton impact structure. Refractive indices of the diaplectic and fused components of the gneisses, and reduced specific gravity indicate shock pressures from 35 to 55±5 GPa and effective post-shock temperatures from 500° to 1,000° C in a suite of selected samples. Sillimanites remain birefringent but display several effects of shock metamorphism. Shock-produced planar features and planar fractures are highly developed; optic axial angle (2V y ) increases from near normal (26°) to over 80° within a sample; there is a reduction in optical relief and a development of a pale brown colouring which generally deepens in shade as shock level increases. There is no unambiguous evidence, optically or from X-ray investigation, of a high-pressure Al2SiO5 polymorph or breakdown to mullite and silica. The highly shocked sillimanites have anomalous K2O contents from 0.11% to 0.92%. Potassium appears to substitute for aluminum and, to a lesser degree, for iron while retaining sillimanite stoichiometry, and the amount of substitution generally reflects increased shock level. The source of the contributed potassium is the coexisting shock-fused feldspar glass. The glass of each sample is derived primarily from melted alkali feldspar with a minor and varied admixture from the breakdown of mafic minerals. The glasses are depleted in K2O, although Na2O is unaffected, and the extent of depletion can be correlated with the increased K2O content of the associated sillimanite. The incorporation of potassium in shocked sillimanites is a function of both degree of shock deformation and availability of potassium from other coexisting shocked phases. It is speculated that the brown colouration is a function of ferrous iron content and may reflect post-crater thermal history rather than shock level.

Notes: Abstract Major elements, trace elements and 87Sr/86Sr data are reported for the Quaternary potassic alkaline rocks from the Mts. Ernici volcanic area (Southern Latium — Italy). These rocks are represented by primitive types which display high Mgv, low D.I., variable degrees of silica undersaturation and different K2O contents which allowed the distinction of a potassium series (KS) and a high potassium series (HKS). All the analyzed samples have high LIL element contents and high 87Sr/86Sr which ranges between 0.707–0.711. They also have fractionated REE patterns. The KS rocks have lower LIL element concentrations and 87Sr/86Sr ratios than the HKS rocks with a large compositional gap between the two series. Minor but still significant isotopic and trace element variations are also observed within both KS and HKS. The genesis cannot be completly explained either by crystal liquid fractionation, mixing or assimilation processes or by different degrees of equilibrium partial melting from a homogeneous source, thus indicating that both the KS and HKS consist of several geochemically and isotopically distinct magma types. The data suggest that the KS and HKS magmas originated by low degrees of melting of a garnet peridotite mantle heterogeneously enriched in LIL elements and radiogenic strontium, possibly accompanied by disquilibrium melting of some accessory phases. The occurrence of a geochemical anomaly within the mantle is believed to be due to fluid metasomatism probably generated by dehydration of a lithospheric slab subducted during the Late Tertiary development of the Apennine Chain.

Notes: Zusammenfassung Wegeners Expeditionen haben viele Messungen angeregt, die zu Ergebnissen geführt haben, die nunmehr reif sind für Computer-Modelle von Eisdecken. Es werden die Fortschritte in der Kenntnis von Akkumulationsraten, Mächtigkeit, Temperatur, Kristallstruktur, Oberflächenkartierung von Eisdecken und Verunreinigungen umrissen. Danach wird die Arbeit mit dem Computer-Modell diskutiert. Der Wert solcher Untersuchungen für großmaßstäbliche Tests geophysikalischer Konzepte wird betont. Die Ergebnisse lassen erwarten, daß die Schubkräfte der kontinentalen Eisdecken auf dem Top der kontinentalen Blöcke in derselben Größenordnung liegen könnten wie die aus der Bewegung der Asthenosphäre an der Basis dieser Blöcke. Letztere könnten damit kompensiert werden. Unabhängig davon, daß die aufgestellte Hypothese mögliche Argumente für die aseismische Natur der Antarktischen und Grönland-Massen aufzeigt, verbindet sie im Rahmen dieses Bandes Wegeners Interesse an kontinentalen Eisdecken mit der Kontinentaldrift.

Notes: Zusammenfassung Verschiedene multivariate Modelle die zurückgreifend die Sonneneinstrahlung ausausgewählter Monate und Breitengrade kombinieren, erklären 55% bis 67% der gesamten klimatischen Variation der letzten 135 000 Jahre, die durch Sauerstoffisotopen-Daten belegt wurden. Diese monatlichen Sonneneinstrahlungen wurden nach einer neuen astronomischen Lösung für die Elemente der Erdbahn berechnet. Diese Lösung ist aus der zweiten Ordnung der Masse und dem dritten Grad der Exzentrizitäten und der Inklinationen berechnet (Berger, 1978 a). Ohne menschliches Eingreifen ergibt sich aus den Modellen eine Abkühlung, deren Höchstwert zwischen 3000 und 6000 Jahren nach unserer Zeit erreicht sein wird. Nach einer fühlbaren Verbesserung des Klimas ergibt sich eine weitere, strengere Abkühlung in etwa 60 000 Jahren.

Notes: Zusammenfassung Periglaziale Forschung begann mit frühen Mitteilungen über Permafrost in der Sowjet-Union, aber der Ausdruck periglazial und die Verwendung von periglazialen Formen in Paleostudien stammen von Łozinski in Polen. Einen starken Impuls zur Entwicklung dieser Wissenschaft gab die Exkursion des 11. International Geologischen Kongresses nach Spitsbergen im Jahre 1910, an der sehr prominente Geologen ihrer Zeit teilnahmen und deren Berichte über die damals wenig bekannten periglazialen Formen große Beachtung fanden. Es gibt heute eine enorme interdisziplinäre Literatur, die geographische, geologische, paleoklimatische, technische und unweltliche Disziplinen umfaßt. Untersuchungen über Prozesse betreffen Frostspaltung, Frosthebung, Frostsprengung, Kryosolifluktion, Kryoplanationterrassen, Pingos und die vielen Formen von Frost-Musterböden. Laborforschung über Forsthebung wurde vonTaber im Jahre 1929 betrieben und nahm wegen ihrer geotechnischen Implikationen ständig an Bedeutung zu. Das französische Centre de Géomorphologie (CNRS) in Caen, das russische Institut Merzlotovedeniya in Yakutsk und das U.S. Army Cold Regions Research and Engineering Laboratory in Hanover, N. H., sind staatliche Forschungszentren, die speziell für solche Forschungen errichtet wurden. Unzählige ungelöste Probleme bleiben bestehen, zum Beispiel (1) die Wirksamkeit von Frostsprengung gegenüber dem Orientierungswechsel von Wassermolekülen in periglazialen Gegenden, (2) die Bedeutung von Frostschub im Vergleich zu Kryosilifluktion, (3) der genaue Prozeß in rückläufigen Bewegungen im Frostschub, (4) die Mechanik von Kryosolifluktion, (5) der Ursprung von verschiedenen Formen von Frostmusterböden, (6) der Ursprung beträchtlicher tafelartiger Vorkommnisse von massivem Bodeneis, (7) Beschaffenheit und Verteilung von submarinem Permafrost, (8) Identifizierung der Unterschiede zwischen Kryokarstvertiefungen und Gletschersöllen, und (9) die klimatische Bedeutung von verschiedenen periglazialen Formen unter Einbeziehung von Temperatur, Niederschlag und anderen Faktoren. Fortschreitende regionale Studien und Untersuchungen über Prozesse haben die paleoklimatischen Aspekte der periglazialen Forschung unterstützt, wobei in Deutschland die klassischen Beiträge von Büdel, Kessler, Soergel, und Troll unter anderen vorzuheben sind. Es ist jetzt klar, daß die wichtigsten periglazialen Merkmale für klimatische und andere Umweltsrekonstruktionen die sind, die auf Permafrost hinweisen. Eine bedeutende Schwierigkeit in der Anwendung von relikt- oder fossil-periglazialen Formen als quantitative Indizien für früheres Klima stellt der Einfluß von Faktoren wie Schneedecke und Vegetation dar. Trotzdem können bestimmte Formen zur groben Schätzung von früheren maximal möglichen mittleren Jahreslufttemperaturen dienen. Die wichtigsten sind (1) Relikt-Permafrost (0° C) und (2) fossile Formen von Strukturböden mit einem Durchmesser von mehr als 2 m (0° C), (3) Pingos vom offenen Systemtyp (−2° C), (4) Eiskeil-Netze (z. B. Eiskeil-Pseudomorphosen) und wahrscheinlich auch gut entwickelte Bodenkeile (−5° C), und (5) Pingos vom geschlossenen Systemtyp (−6° C). Die klimatische Bedeutung von Kryoplanationsterrassen bleibt noch zu klären; sie könnten jedoch ein sehr wichtiger Beleg sein.

Notes: Zusammenfassung Ausgangspunkt der Wegenerschen Theorie war der unmittelbare Eindruck von der Kongruenz der atlantischen Küsten. Das eigentliche Fundament bildeten jedoch die Argumente aus Paläontologie, Geophysik, Geologie, Paläoklimatologie und Astrogeodäsie. Wegener war nicht nur der Schöpfer, sondern auch der Propagandist seiner Theorie. Von bleibendem Wert erwiesen sich seine Forderungen: Jede Theorie der Entstehung der Ozeane und Kontinente muß von allen geowissenschaftlichen Disziplinen getragen werden und sie muß sich durch Messungen bestätigen lassen.

Notes: Zusammenfassung 15 Paare von paläoglobalen Karten werden hier nach einer Lambertschen flächengetreuen Projektion mit Hilfe eines Rechnerprogrammes dargestellt. Der Zeitabschnitt umfaßt in 40 Mill. Jahres-Schritten die letzten 560 Mill. Jahre seit dem Kambrium.

Notes: Zusammenfassung Die Mittelmeer-Mjösen-ZoneStilles erfährt durch die zeitliche Abfolge von Ortho- und Para-Oberrheingraben eine Wandlung, so daß beim heutigen tektonischen Geschehen von einem Mittelmeer-Rhein-Nordsee-Graben als bedeutendste Trennfuge von Europa gesprochen werden kann. Verbindungen zu den zentralen Riftsystemen des Indischen und Nord-Atlantischen Ozeans sind wahrscheinlich. Der Verlauf der variscischen Becken- und Schwellenachsen, der tertiäre Vulkanismus in der nordwestlichen Fortsetzung des Bayerischen Pfahles und bedeutende hercynisch streichende Ganglagerstätten zeigen Beziehungen zum tertiären bis rezenten Vorlanddruck des Alpenkörpers auf.

Notes: Zusammenfassung Der Atlantik ist heute das einzige Tiefwasserbecken, das die nördlichen und südlichen Bildungsgebiete kalter polarer Bodenwässer verbindet. Sein Aufbrechen und Wachstum während der vergangenen 140–180 Millionen Jahre bewirkte wichtige Veränderungen der Paläo-Ozeanographie des Weltmeeres und der Ablagerungsräume der benachbarten Kontinente. Die schrittweise Entwicklung der Teilbecken des Nordatlantiks, die Geschichte und die endgültige Unterbrechung des zirkumäquatorialen, tropischen Tethys-Ozeans, das Wachsen und Schrumpfen der Schelfmeere, die Zerstörung submariner Schwellen und das Zerbrechen von Landbrücken bewirkten kräftige Veränderungen des pelagischen Ablagerungsmilieus, die nach den ersten 10 Jahren des Tiefseebohrprojektes im Detail untersucht werden können. Zeitspannen hoher pelagischer Sedimentationsraten vor 140-110, 55-45 und während der letzten 25 Millionen Jahre wechselten mit Phasen geringer Sedimentation im Nordatlantik. Hohe relative eustatische Meeresspiegel scheinen zeitlich mit niedrigen Sedimentationsraten dieser Tiefseeablagerungen, die zum größten Teil aus Karbonat planktonischer Herkunft bestehen, zusammenzufallen. Diese Beobachtungen stützen die Hypothese einer Sedimentfraktionierung zwischen den tiefen und flachen Gebieten des Weltmeeres. Klastische terrigene Komponenten sind relativ selten in den mesozoischen und känozoischen Tiefseeablagerungen des Nordatlantiks. Terrigenes klastisches Material scheint die Tiefseebecken des Nordatlantiks während des oberen Juras und während der unteren Kreide kaum erreicht zu haben, aber vor ungefähr 90–100 Millionen Jahre wurden plötzlich größere Mengen klastischen Materials in den Nordatlantik geschüttet. Seit der oberen Kreide sind die nordatlantischen Gebiete hoher Konzentrationen klastischen Materials hauptsächlich auf die Tiefsee-Ebene beschränkt; die größten Mengen dieses Materials erreichten die Tiefsee-Ebenen, während sich weiträumige Schichtlücken bildeten.

Notes: Zusammenfassung Das Graben-Mantelkissen-Modell, welches für das nördliche Hesperische Massiv von drei der Autoren (v. C., d. T., K.) entwickelt wurde, wird zu dem eines aulacogenen ensialischen Orogens für das ganze Massiv weiterentwickelt. Der erste Autor (v. d. M. M.) liefert eine Übersicht der suprakrustalen Entwicklungsgeschichte des Massivs und seiner Umrandung vor der Driftung, zusammengefaßt in einer stratigraphischen Tabelle des Kambro-Ordoviziums und in einer palinspastisch-paleogeographischen Skizze der Region während des Mittelkambriums. Die infrastrukturale Entwicklungsgeschichte wird ebenfalls beleuchtet, und es wird daraus geschlossen, daß die frühpaläozoischen Konfigurationen des Massivs mit denen eines Aulacogens übereinstimmen, unter Einschluß eines großen Winkels mit dem Iapetus Ozean. Im Jungpaläozoikum veränderten sich die Charakteristika zu denen eines ensialischen Orogens, ohne daß, im weiteren Verlauf der Erdgeschichte, dieser Prozeß unterbrochen wurde, wie sedimentäre Fazies, Altersdatierungen und kristalline und metamorphe Entwicklung dokumentieren.

Notes: Zusammenfassung Sowohl in Arabien, ne-Afrika und auf den den Atlantik umgebenden kontinentalen Tafeln können große, epirogene Wellenwürfe ausgemacht werden. All diese Undulation-Systeme sind im Streichen parallel zu benachbarten Riftsystemen ausgerichtet, und ihre Wellenlänge nimmt mit Abstand vom Rifttrog zu. Die Untersuchungen am arabischen Beispiel zu den Zusammenhängen zwischen Bildung ozeanischer Kruste einerseits und deren tektonischen Auswirkungen auf kontinentale Tafeln, wie Magmatismus, Orogenese und besonders in intra-platten dynamischer Hinsicht andererseits, scheinen neue Gesichtspunkte zur Paläogeographie zu eröffnen, und zum Verstehen der Ursachen und Evolution der Schildwellungen beizutragen. Sie zeigen, daß die Schildwellungen nicht im vollen morphologischen Ausmaß mit Beginn des Rifting einsetzen, sondern die Schildbereiche allmählich von der Riftseite her durchdringen (± 40 m. a.) und etwa 80 m. a. zur Vollentwicklung brauchen. Rift-parallele Becken und Schwellen sind in Rift-Nähe am ältesten und werden mit Abstand von letzeren jünger. Über die paläogeographischen Entwicklungen kann ferner gezeigt werden, daß der Wellungs-Prozeß nicht kontinuierlich, sondern in Schüben verläuft. Blattverschiebungen im Rahmen diagonal angelegter Scherung sind eine konjugate Reaktion zur kompressionellen Wellung oder Faltung. Große und kleinere Störungen oder Störungssysteme dieser Kategorie sind im Bereich der Schildwellungen fast immer vorhanden. Schildwellung, die in dieser Arbeit absichtlich etwas überbetont wird, scheint auf alten, auf tiefe Stockwerke erodierten und stark konsilidierten Kratonen gegenüber Scherung zu überwiegen (z. B. Arabischer Schild), während Scherung und Bruchschollen-Tektonik im Sedimentmantel jüngerer, wenig tief erodierter und wohl möglich weniger konsolidierter, kratonisierter Areale ausgeprägter ist (z. B. Europäisches Schollenmosaik). Es wird abgeleitet, daß die Schildwellungen wie die Scherungstektonik von horizontalen, kompressioneilen Verspannungen ausgelöst werden und letztere mit der Bildung und Ausbreitung ozeanischer Kruste (Mantel-Diapirismus, Ocean-Floor Spreading) in ursächlichem Zusammenhang stehen. Die aus tektonischen Gründen vermutete kompressionelle Verspanung kontinentaler Tafeln und deren Symmetriebindung an das „world rift system“ scheint sich nunmehr durch direkte Messungen zu bestätigen, jedenfalls passen sowohl seismo-tektonische Herdmechanismen-Analysen, wie in situ-Druckmessungen in Europa ausgezeichnet zum tektonischen Modell. Arabien wird als Modell-Beispiel für Schildwellungen im Rahmen geodynamischer Beanspruchungen angesehen.